/src/libxmlb/src/xb-silo.c

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/*
 * Copyright 2018 Richard Hughes <richard@hughsie.com>
 *
 * SPDX-License-Identifier: LGPL-2.1-or-later
 */

/**
 * SECTION:xb-silo
 * @title: XbSilo
 * @include: xmlb.h
 * @stability: Stable
 * @short_description: A read-only store of parsed XML data
 *
 * #XbSilo provides read-only access and querying of a previously parsed blob
 * of XML data.
 *
 * All signal emissions from #XbSilo (currently only #GObject::notify emissions)
 * will happen in the #GMainContext which is the thread default when the #XbSilo
 * is constructed.
 *
 * This #GMainContext must be iterated for file monitoring using
 * xb_silo_watch_file() to function correctly.
 */

#define G_LOG_DOMAIN "XbSilo"

#include "config.h"

#include <gio/gio.h>
#include <glib-object.h>
#include <string.h>

#ifdef HAVE_LIBSTEMMER
#include <libstemmer.h>
#endif

#include "xb-builder.h"
#include "xb-common-private.h"
#include "xb-machine-private.h"
#include "xb-node-private.h"
#include "xb-opcode-private.h"
#include "xb-silo-node.h"
#include "xb-stack-private.h"
#include "xb-string-private.h"

typedef struct {
  GMappedFile *mmap;
  gchar *guid;
  gboolean valid;
  GBytes *blob;
  const guint8 *data; /* pointers into ->blob */
  guint32 datasz;
  guint32 strtab;
  GHashTable *strtab_tags;
  GHashTable *strindex;
  gboolean enable_node_cache;
  GHashTable *nodes; /* (mutex nodes_mutex) */
  GMutex nodes_mutex;
  GHashTable *file_monitors; /* (element-type GFile XbSiloFileMonitorItem) (mutex
              file_monitors_mutex) */
  GMutex file_monitors_mutex;
  XbMachine *machine;
  XbSiloProfileFlags profile_flags;
  GString *profile_str;
  GRWLock query_cache_mutex;
  GHashTable *query_cache;
  GMainContext *context; /* (owned) */
#ifdef HAVE_LIBSTEMMER
  struct sb_stemmer *stemmer_ctx; /* lazy loaded */
  GMutex stemmer_mutex;
#endif
} XbSiloPrivate;

typedef struct {
  GFileMonitor *file_monitor;
  gulong file_monitor_id;
} XbSiloFileMonitorItem;

G_DEFINE_TYPE_WITH_PRIVATE(XbSilo, xb_silo, G_TYPE_OBJECT)
#define GET_PRIVATE(o) (xb_silo_get_instance_private(o))

typedef enum {
  PROP_GUID = 1,
  PROP_VALID,
  PROP_ENABLE_NODE_CACHE,
} XbSiloProperty;

static GParamSpec *obj_props[PROP_ENABLE_NODE_CACHE + 1] = {
    NULL,
};

/* private */
GTimer *
xb_silo_start_profile(XbSilo *self)
{
  XbSiloPrivate *priv = GET_PRIVATE(self);

  /* nothing to do; g_timer_new() does a syscall to clock_gettime() which
   * is best avoided if not needed */
  if (!priv->profile_flags)
    return NULL;

  return g_timer_new();
}

/* private */
void
xb_silo_add_profile(XbSilo *self, GTimer *timer, const gchar *fmt, ...)
{
  XbSiloPrivate *priv = GET_PRIVATE(self);
  va_list args;
  g_autoptr(GString) str = NULL;

  /* nothing to do */
  if (!priv->profile_flags)
    return;

  str = g_string_new("");

  /* add duration */
  if (timer != NULL) {
    g_string_append_printf(str, "%.2fms", g_timer_elapsed(timer, NULL) * 1000);
    for (guint i = str->len; i < 12; i++)
      g_string_append(str, " ");
  }

  /* add varargs */
  va_start(args, fmt);
  g_string_append_vprintf(str, fmt, args);
  va_end(args);

  /* do the right thing */
  if (priv->profile_flags & XB_SILO_PROFILE_FLAG_DEBUG)
    g_debug("%s", str->str);
  if (priv->profile_flags & XB_SILO_PROFILE_FLAG_APPEND)
    g_string_append_printf(priv->profile_str, "%s\n", str->str);

  /* reset automatically */
  if (timer != NULL)
    g_timer_reset(timer);
}

/* private */
static gchar *
xb_silo_stem(XbSilo *self, const gchar *value)
{
#ifdef HAVE_LIBSTEMMER
  XbSiloPrivate *priv = GET_PRIVATE(self);
  const gchar *tmp;
  gsize len_dst;
  gsize len_src;
  g_autofree gchar *value_casefold = NULL;
  g_autoptr(GMutexLocker) locker = g_mutex_locker_new(&priv->stemmer_mutex);

  g_return_val_if_fail(locker != NULL, NULL);

  /* not enabled */
  value_casefold = g_utf8_casefold(value, -1);
  if (priv->stemmer_ctx == NULL)
    priv->stemmer_ctx = sb_stemmer_new("en", NULL);

  /* stem */
  len_src = strlen(value_casefold);
  tmp = (const gchar *)sb_stemmer_stem(priv->stemmer_ctx,
               (guchar *)value_casefold,
               (gint)len_src);
  len_dst = (gsize)sb_stemmer_length(priv->stemmer_ctx);
  if (len_src == len_dst)
    return g_steal_pointer(&value_casefold);
  return g_strndup(tmp, len_dst);
#else
  return g_utf8_casefold(value, -1);
#endif
}

/* private */
const gchar *
xb_silo_from_strtab(XbSilo *self, guint32 offset, GError **error)
{
  XbSiloPrivate *priv = GET_PRIVATE(self);
  if (G_UNLIKELY(offset == XB_SILO_UNSET)) {
    g_set_error_literal(error, G_IO_ERROR, G_IO_ERROR_NOT_FOUND, "offset was unset");
    return NULL;
  }
  if (offset >= priv->datasz - priv->strtab) {
    g_set_error(error,
          G_IO_ERROR,
          G_IO_ERROR_INVALID_DATA,
          "strtab+offset is outside the data range for %u",
          offset);
    return NULL;
  }
  return (const gchar *)(priv->data + priv->strtab + offset);
}

/* private */
gboolean
xb_silo_strtab_index_insert(XbSilo *self, guint32 offset, GError **error)
{
  XbSiloPrivate *priv = GET_PRIVATE(self);
  const gchar *tmp;

  /* get the string version */
  tmp = xb_silo_from_strtab(self, offset, error);
  if (tmp == NULL)
    return FALSE;
  if (g_hash_table_lookup(priv->strindex, tmp) != NULL)
    return TRUE;
  g_hash_table_insert(priv->strindex, (gpointer)tmp, GUINT_TO_POINTER(offset));
  return TRUE;
}

/* private */
guint32
xb_silo_strtab_index_lookup(XbSilo *self, const gchar *str)
{
  XbSiloPrivate *priv = GET_PRIVATE(self);
  gpointer val = NULL;
  if (!g_hash_table_lookup_extended(priv->strindex, str, NULL, &val))
    return XB_SILO_UNSET;
  return GPOINTER_TO_INT(val);
}

/* private */
XbSiloNode *
xb_silo_get_node(XbSilo *self, guint32 off, GError **error)
{
  XbSiloPrivate *priv = GET_PRIVATE(self);
  if (G_UNLIKELY(off >= priv->strtab)) {
    g_set_error(error,
          G_IO_ERROR,
          G_IO_ERROR_INVALID_DATA,
          "offset %u is outside the expected range",
          off);
    return NULL;
  }
  return (XbSiloNode *)(priv->data + off);
}

/* private */
guint32
xb_silo_get_offset_for_node(XbSilo *self, XbSiloNode *n)
{
  XbSiloPrivate *priv = GET_PRIVATE(self);
  return ((const guint8 *)n) - priv->data;
}

/* private */
guint32
xb_silo_get_strtab(XbSilo *self)
{
  XbSiloPrivate *priv = GET_PRIVATE(self);
  return priv->strtab;
}

/* private */
XbSiloNode *
xb_silo_get_root_node(XbSilo *self, GError **error)
{
  XbSiloPrivate *priv = GET_PRIVATE(self);
  if (G_UNLIKELY(priv->blob == NULL)) {
    g_set_error_literal(error, G_IO_ERROR, G_IO_ERROR_INVALID_DATA, "no blob loaded");
    return NULL;
  }
  if (G_UNLIKELY(g_bytes_get_size(priv->blob) < sizeof(XbSiloHeader))) {
    g_set_error(error,
          G_IO_ERROR,
          G_IO_ERROR_INVALID_DATA,
          "blob too small: 0x%x",
          (guint)g_bytes_get_size(priv->blob));
    return NULL;
  }
  if (G_UNLIKELY(g_bytes_get_size(priv->blob) == sizeof(XbSiloHeader))) {
    g_set_error_literal(error, G_IO_ERROR, G_IO_ERROR_NOT_FOUND, "no node data");
    return NULL;
  }
  return xb_silo_get_node(self, sizeof(XbSiloHeader), error);
}

/* private */
XbSiloNode *
xb_silo_get_parent_node(XbSilo *self, XbSiloNode *n, GError **error)
{
  if (G_UNLIKELY(n->parent == 0x0)) {
    g_set_error(error,
          G_IO_ERROR,
          G_IO_ERROR_INVALID_ARGUMENT,
          "no parent set for %s",
          xb_silo_get_node_element(self, n, NULL));
    return NULL;
  }
  return xb_silo_get_node(self, n->parent, error);
}

/* private */
XbSiloNode *
xb_silo_get_next_node(XbSilo *self, XbSiloNode *n, GError **error)
{
  if (n->next == 0x0) {
    g_set_error_literal(error, G_IO_ERROR, G_IO_ERROR_INVALID_ARGUMENT, "no next node");
    return NULL;
  }
  return xb_silo_get_node(self, n->next, error);
}

/* private */
XbSiloNode *
xb_silo_get_child_node(XbSilo *self, XbSiloNode *n, GError **error)
{
  XbSiloNode *c;
  guint32 off = xb_silo_get_offset_for_node(self, n);
  off += xb_silo_node_get_size(n);

  /* check for sentinel */
  c = xb_silo_get_node(self, off, error);
  if (c == NULL)
    return NULL;
  if (!xb_silo_node_has_flag(c, XB_SILO_NODE_FLAG_IS_ELEMENT)) {
    g_set_error_literal(error,
            G_IO_ERROR,
            G_IO_ERROR_INVALID_ARGUMENT,
            "no child element");
    return NULL;
  }
  return c;
}

/**
 * xb_silo_get_root:
 * @self: a #XbSilo
 *
 * Gets the root node for the silo. (MIGHT BE MORE).
 *
 * Returns: (transfer full): A #XbNode, or %NULL for an error
 *
 * Since: 0.1.0
 **/
XbNode *
xb_silo_get_root(XbSilo *self)
{
  XbSiloNode *sn;
  g_autoptr(GError) error_local = NULL;

  g_return_val_if_fail(XB_IS_SILO(self), NULL);

  sn = xb_silo_get_root_node(self, &error_local);
  if (sn == NULL) {
    /* if there are no XbSiloNodes, still build a root XbNode */
    if (!g_error_matches(error_local, G_IO_ERROR, G_IO_ERROR_NOT_FOUND))
      return NULL;
    g_debug("ignoring: %s", error_local->message);
  }
  return xb_silo_create_node(self, sn, FALSE);
}

/* private */
guint32
xb_silo_get_strtab_idx(XbSilo *self, const gchar *element)
{
  XbSiloPrivate *priv = GET_PRIVATE(self);
  gpointer value = NULL;
  if (!g_hash_table_lookup_extended(priv->strtab_tags, element, NULL, &value))
    return XB_SILO_UNSET;
  return GPOINTER_TO_UINT(value);
}

/**
 * xb_silo_to_string:
 * @self: a #XbSilo
 * @error: the #GError, or %NULL
 *
 * Converts the silo to an internal string representation. This is only
 * really useful for debugging #XbSilo itself.
 *
 * Returns: A string, or %NULL for an error
 *
 * Since: 0.1.0
 **/
gchar *
xb_silo_to_string(XbSilo *self, GError **error)
{
  guint32 off = sizeof(XbSiloHeader);
  XbSiloPrivate *priv = GET_PRIVATE(self);
  XbSiloHeader *hdr = (XbSiloHeader *)priv->data;
  g_autoptr(GString) str = g_string_new(NULL);

  g_return_val_if_fail(XB_IS_SILO(self), NULL);
  g_return_val_if_fail(error == NULL || *error == NULL, NULL);

  /* sanity check */
  if (hdr->strtab > priv->datasz) {
    g_set_error_literal(error, G_IO_ERROR, G_IO_ERROR_INVALID_DATA, "strtab invalid");
    return NULL;
  }

  g_string_append_printf(str, "magic:        %08x\n", (guint)hdr->magic);
  g_string_append_printf(str, "guid:         %s\n", priv->guid);
  g_string_append_printf(str, "filesz:       @%" G_GUINT64_FORMAT "\n", hdr->filesz);
  g_string_append_printf(str, "strtab:       @%" G_GUINT32_FORMAT "\n", hdr->strtab);
  g_string_append_printf(str, "strtab_ntags: %" G_GUINT16_FORMAT "\n", hdr->strtab_ntags);
  while (off < priv->strtab) {
    XbSiloNode *n = xb_silo_get_node(self, off, error);
    if (n == NULL)
      return NULL;
    if (xb_silo_node_has_flag(n, XB_SILO_NODE_FLAG_IS_ELEMENT)) {
      guint32 idx;
      const gchar *element_name;
      g_string_append_printf(str, "NODE @%" G_GUINT32_FORMAT "\n", off);
      g_string_append_printf(str,
                 "size:         %" G_GUINT32_FORMAT "\n",
                 xb_silo_node_get_size(n));
      g_string_append_printf(str,
                 "flags:        %x\n",
                 xb_silo_node_get_flags(n));
      element_name = xb_silo_from_strtab(self, n->element_name, error);
      if (element_name == NULL)
        return NULL;
      g_string_append_printf(str,
                 "element_name: %s [%03u]\n",
                 element_name,
                 n->element_name);
      g_string_append_printf(str,
                 "next:         %" G_GUINT32_FORMAT "\n",
                 n->next);
      g_string_append_printf(str,
                 "parent:       %" G_GUINT32_FORMAT "\n",
                 n->parent);
      idx = xb_silo_node_get_text_idx(n);
      if (idx != XB_SILO_UNSET) {
        const gchar *text = xb_silo_from_strtab(self, idx, error);
        if (text == NULL)
          return NULL;
        g_string_append_printf(str, "text:         %s [%03u]\n", text, idx);
      }
      idx = xb_silo_node_get_tail_idx(n);
      if (idx != XB_SILO_UNSET) {
        const gchar *tail = xb_silo_from_strtab(self, idx, error);
        if (tail == NULL)
          return NULL;
        g_string_append_printf(str, "tail:         %s [%03u]\n", tail, idx);
      }
      for (guint8 i = 0; i < xb_silo_node_get_attr_count(n); i++) {
        XbSiloNodeAttr *a = xb_silo_node_get_attr(n, i);
        const gchar *attr_name;
        const gchar *attr_value;

        attr_name = xb_silo_from_strtab(self, a->attr_name, error);
        if (attr_name == NULL)
          return NULL;
        g_string_append_printf(str,
                   "attr_name:    %s [%03u]\n",
                   attr_name,
                   a->attr_name);
        attr_value = xb_silo_from_strtab(self, a->attr_value, error);
        if (attr_value == NULL)
          return NULL;
        g_string_append_printf(str,
                   "attr_value:   %s [%03u]\n",
                   attr_value,
                   a->attr_value);
      }
      for (guint8 i = 0; i < xb_silo_node_get_token_count(n); i++) {
        guint32 idx_tmp = xb_silo_node_get_token_idx(n, i);
        const gchar *token = xb_silo_from_strtab(self, idx_tmp, error);
        if (token == NULL)
          return NULL;
        g_string_append_printf(str,
                   "token:        %s [%03u]\n",
                   token,
                   idx_tmp);
      }
    } else {
      g_string_append_printf(str, "SENT @%" G_GUINT32_FORMAT "\n", off);
    }
    off += xb_silo_node_get_size(n);
  }

  /* add strtab */
  g_string_append_printf(str, "STRTAB @%" G_GUINT32_FORMAT "\n", hdr->strtab);
  for (off = 0; off < priv->datasz - hdr->strtab;) {
    const gchar *tmp = xb_silo_from_strtab(self, off, NULL);
    if (tmp == NULL)
      break;
    g_string_append_printf(str, "[%03u]: %s\n", off, tmp);
    off += strlen(tmp) + 1;
  }

  /* success */
  return g_string_free(g_steal_pointer(&str), FALSE);
}

/* private */
const gchar *
xb_silo_get_node_element(XbSilo *self, XbSiloNode *n, GError **error)
{
  return xb_silo_from_strtab(self, n->element_name, error);
}

/* private */
XbSiloNodeAttr *
xb_silo_get_node_attr_by_str(XbSilo *self, XbSiloNode *n, const gchar *name)
{
  guint8 attr_count;

  /* calculate offset to first attribute */
  attr_count = xb_silo_node_get_attr_count(n);
  for (guint8 i = 0; i < attr_count; i++) {
    XbSiloNodeAttr *a = xb_silo_node_get_attr(n, i);
    const gchar *name_tmp = xb_silo_from_strtab(self, a->attr_name, NULL);
    if (name_tmp == NULL)
      return NULL;
    if (g_strcmp0(name_tmp, name) == 0)
      return a;
  }

  /* nothing matched */
  return NULL;
}

static XbSiloNodeAttr *
xb_silo_node_get_attr_by_val(XbSilo *self, XbSiloNode *n, guint32 name)
{
  guint8 attr_count;

  /* calculate offset to first attribute */
  attr_count = xb_silo_node_get_attr_count(n);
  for (guint8 i = 0; i < attr_count; i++) {
    XbSiloNodeAttr *a = xb_silo_node_get_attr(n, i);
    if (a->attr_name == name)
      return a;
  }

  /* nothing matched */
  return NULL;
}

/**
 * xb_silo_get_size:
 * @self: a #XbSilo
 *
 * Gets the number of nodes in the silo.
 *
 * Returns: a integer, or 0 is an empty blob
 *
 * Since: 0.1.0
 **/
guint
xb_silo_get_size(XbSilo *self)
{
  XbSiloPrivate *priv = GET_PRIVATE(self);
  guint32 off = sizeof(XbSiloHeader);
  guint nodes_cnt = 0;

  g_return_val_if_fail(XB_IS_SILO(self), 0);

  while (off < priv->strtab) {
    XbSiloNode *n = xb_silo_get_node(self, off, NULL);
    if (n == NULL)
      return 0;
    if (xb_silo_node_has_flag(n, XB_SILO_NODE_FLAG_IS_ELEMENT))
      nodes_cnt += 1;
    off += xb_silo_node_get_size(n);
  }

  /* success */
  return nodes_cnt;
}

/**
 * xb_silo_is_valid:
 * @self: a #XbSilo
 *
 * Checks is the silo is valid. The usual reason the silo is invalidated is
 * when the backing mmapped file has changed, or one of the imported files have
 * been modified.
 *
 * Returns: %TRUE if valid
 *
 * Since: 0.1.0
 **/
gboolean
xb_silo_is_valid(XbSilo *self)
{
  XbSiloPrivate *priv = GET_PRIVATE(self);
  g_return_val_if_fail(XB_IS_SILO(self), FALSE);
  return priv->valid;
}

/* private */
gboolean
xb_silo_is_empty(XbSilo *self)
{
  XbSiloPrivate *priv = GET_PRIVATE(self);
  g_return_val_if_fail(XB_IS_SILO(self), FALSE);
  return priv->strtab == sizeof(XbSiloHeader);
}

typedef struct {
  XbSilo *silo;    /* (owned) */
  GParamSpec *pspec; /* (owned) */
} SiloNotifyData;

static void
silo_notify_data_free(SiloNotifyData *data)
{
  g_clear_object(&data->silo);
  g_clear_pointer(&data->pspec, g_param_spec_unref);
  g_free(data);
}

G_DEFINE_AUTOPTR_CLEANUP_FUNC(SiloNotifyData, silo_notify_data_free)

static gboolean
silo_notify_cb(gpointer user_data)
{
  g_autoptr(SiloNotifyData) data = g_steal_pointer(&user_data);

  g_object_notify_by_pspec(G_OBJECT(data->silo), data->pspec);

  return G_SOURCE_REMOVE;
}

/* Like g_object_notify(), but ensure that the signal is emitted in XbSilo.context. */
static void
silo_notify(XbSilo *self, GParamSpec *pspec)
{
  XbSiloPrivate *priv = GET_PRIVATE(self);
  g_autoptr(SiloNotifyData) data = NULL;

  data = g_new0(SiloNotifyData, 1);
  data->silo = g_object_ref(self);
  data->pspec = g_param_spec_ref(pspec);

  g_main_context_invoke(priv->context, silo_notify_cb, g_steal_pointer(&data));
}

/**
 * xb_silo_invalidate:
 * @self: a #XbSilo
 *
 * Invalidates a silo. Future calls xb_silo_is_valid() will return %FALSE.
 *
 * Since: 0.1.1
 **/
void
xb_silo_invalidate(XbSilo *self)
{
  XbSiloPrivate *priv = GET_PRIVATE(self);
  if (!priv->valid)
    return;
  priv->valid = FALSE;
  silo_notify(self, obj_props[PROP_VALID]);
}

/* private */
void
xb_silo_uninvalidate(XbSilo *self)
{
  XbSiloPrivate *priv = GET_PRIVATE(self);
  if (priv->valid)
    return;
  priv->valid = TRUE;
  silo_notify(self, obj_props[PROP_VALID]);
}

/* private */
guint
xb_silo_get_node_depth(XbSilo *self, XbSiloNode *n)
{
  guint depth = 0;
  while (n->parent != 0) {
    depth++;
    n = xb_silo_get_node(self, n->parent, NULL);
    if (n == NULL)
      break;
  }
  return depth;
}

/**
 * xb_silo_get_bytes:
 * @self: a #XbSilo
 *
 * Gets the backing object that created the blob.
 *
 * You should never *ever* modify this data.
 *
 * Returns: (transfer full): A #GBytes, or %NULL if never set
 *
 * Since: 0.1.0
 **/
GBytes *
xb_silo_get_bytes(XbSilo *self)
{
  XbSiloPrivate *priv = GET_PRIVATE(self);
  g_return_val_if_fail(XB_IS_SILO(self), NULL);
  if (priv->blob == NULL)
    return NULL;
  return g_bytes_ref(priv->blob);
}

/**
 * xb_silo_get_guid:
 * @self: a #XbSilo
 *
 * Gets the GUID used to identify this silo.
 *
 * Returns: a string, otherwise %NULL
 *
 * Since: 0.1.0
 **/
const gchar *
xb_silo_get_guid(XbSilo *self)
{
  XbSiloPrivate *priv = GET_PRIVATE(self);
  g_return_val_if_fail(XB_IS_SILO(self), NULL);
  return priv->guid;
}

/* private */
XbMachine *
xb_silo_get_machine(XbSilo *self)
{
  XbSiloPrivate *priv = GET_PRIVATE(self);
  g_return_val_if_fail(XB_IS_SILO(self), NULL);
  return priv->machine;
}

/**
 * xb_silo_load_from_bytes:
 * @self: a #XbSilo
 * @blob: a #GBytes
 * @flags: #XbSiloLoadFlags, e.g. %XB_SILO_LOAD_FLAG_NONE
 * @error: the #GError, or %NULL
 *
 * Loads a silo from memory location.
 *
 * Returns: %TRUE for success, otherwise @error is set.
 *
 * Since: 0.1.0
 **/
gboolean
xb_silo_load_from_bytes(XbSilo *self, GBytes *blob, XbSiloLoadFlags flags, GError **error)
{
  XbGuid guid_tmp;
  XbSiloHeader *hdr;
  XbSiloPrivate *priv = GET_PRIVATE(self);
  gsize sz = 0;
  guint32 off = 0;
  g_autoptr(GMutexLocker) locker = NULL;
  g_autoptr(GTimer) timer = xb_silo_start_profile(self);

  g_return_val_if_fail(XB_IS_SILO(self), FALSE);
  g_return_val_if_fail(blob != NULL, FALSE);
  g_return_val_if_fail(error == NULL || *error == NULL, FALSE);

  /* no longer valid */
  if (priv->enable_node_cache) {
    locker = g_mutex_locker_new(&priv->nodes_mutex);
    if (priv->nodes != NULL)
      g_hash_table_remove_all(priv->nodes);
  }

  g_hash_table_remove_all(priv->strtab_tags);
  g_clear_pointer(&priv->guid, g_free);

  /* refcount internally */
  if (priv->blob != NULL)
    g_bytes_unref(priv->blob);
  priv->blob = g_bytes_ref(blob);

  /* update pointers into blob */
  priv->data = g_bytes_get_data(priv->blob, &sz);
  priv->datasz = (guint32)sz;

  /* check size */
  if (sz < sizeof(XbSiloHeader)) {
    g_set_error_literal(error, G_IO_ERROR, G_IO_ERROR_INVALID_DATA, "blob too small");
    return FALSE;
  }

  /* check header magic */
  hdr = (XbSiloHeader *)priv->data;
  if ((flags & XB_SILO_LOAD_FLAG_NO_MAGIC) == 0) {
    if (hdr->magic != XB_SILO_MAGIC_BYTES) {
      g_set_error_literal(error,
              G_IO_ERROR,
              G_IO_ERROR_INVALID_DATA,
              "magic incorrect");
      return FALSE;
    }
    if (hdr->version != XB_SILO_VERSION) {
      g_set_error(error,
            G_IO_ERROR,
            G_IO_ERROR_INVALID_DATA,
            "version incorrect, got %u, expected %d",
            hdr->version,
            XB_SILO_VERSION);
      return FALSE;
    }
  }

  /* check size */
  if (hdr->filesz != sz) {
    g_set_error_literal(error, G_IO_ERROR, G_IO_ERROR_INVALID_DATA, "filesz incorrect");
    return FALSE;
  }

  /* get GUID */
  memcpy(&guid_tmp, &hdr->guid, sizeof(guid_tmp));
  priv->guid = xb_guid_to_string(&guid_tmp);

  /* check strtab */
  priv->strtab = hdr->strtab;
  if (priv->strtab > priv->datasz) {
    g_set_error_literal(error, G_IO_ERROR, G_IO_ERROR_INVALID_DATA, "strtab incorrect");
    return FALSE;
  }
  if (hdr->strtab_ntags > 0 && priv->data[sz - 1] != '\0') {
    g_set_error_literal(error,
            G_IO_ERROR,
            G_IO_ERROR_INVALID_DATA,
            "strtab invalid, trailing NUL not found");
    return FALSE;
  }

  /* load strtab_tags */
  for (guint16 i = 0; i < hdr->strtab_ntags; i++) {
    const gchar *tmp = xb_silo_from_strtab(self, off, error);
    if (tmp == NULL) {
      g_prefix_error(error, "strtab_ntags incorrect: ");
      return FALSE;
    }
    g_hash_table_insert(priv->strtab_tags, (gpointer)tmp, GUINT_TO_POINTER(off));
    off += strlen(tmp) + 1;
  }

  /* profile */
  xb_silo_add_profile(self, timer, "parse blob");

  /* success */
  priv->valid = TRUE;
  return TRUE;
}

/**
 * xb_silo_get_profile_string:
 * @self: a #XbSilo
 *
 * Returns the profiling data. This will only return profiling text if
 * xb_silo_set_profile_flags() was used with %XB_SILO_PROFILE_FLAG_APPEND.
 *
 * Returns: text profiling data
 *
 * Since: 0.1.1
 **/
const gchar *
xb_silo_get_profile_string(XbSilo *self)
{
  XbSiloPrivate *priv = GET_PRIVATE(self);
  g_return_val_if_fail(XB_IS_SILO(self), NULL);
  return priv->profile_str->str;
}

/**
 * xb_silo_set_profile_flags:
 * @self: a #XbSilo
 * @profile_flags: some #XbSiloProfileFlags, e.g. %XB_SILO_PROFILE_FLAG_DEBUG
 *
 * Enables or disables the collection of profiling data.
 *
 * Since: 0.1.1
 **/
void
xb_silo_set_profile_flags(XbSilo *self, XbSiloProfileFlags profile_flags)
{
  XbSiloPrivate *priv = GET_PRIVATE(self);
  g_return_if_fail(XB_IS_SILO(self));
  priv->profile_flags = profile_flags;

  /* proxy */
  if (profile_flags & XB_SILO_PROFILE_FLAG_OPTIMIZER) {
    xb_machine_set_debug_flags(priv->machine,
             XB_MACHINE_DEBUG_FLAG_SHOW_OPTIMIZER |
                 XB_MACHINE_DEBUG_FLAG_SHOW_SLOW_PATH);
  }
}

/**
 * xb_silo_get_enable_node_cache:
 * @self: an #XbSilo
 *
 * Get #XbSilo:enable-node-cache.
 *
 * Since: 0.2.0
 */
gboolean
xb_silo_get_enable_node_cache(XbSilo *self)
{
  XbSiloPrivate *priv = GET_PRIVATE(self);
  g_return_val_if_fail(XB_IS_SILO(self), FALSE);
  return priv->enable_node_cache;
}

/**
 * xb_silo_set_enable_node_cache:
 * @self: an #XbSilo
 * @enable_node_cache: %TRUE to enable the node cache, %FALSE otherwise
 *
 * Set #XbSilo:enable-node-cache.
 *
 * This is not thread-safe, and can only be called before the #XbSilo is passed
 * between threads.
 *
 * Since: 0.2.0
 */
void
xb_silo_set_enable_node_cache(XbSilo *self, gboolean enable_node_cache)
{
  XbSiloPrivate *priv = GET_PRIVATE(self);

  g_return_if_fail(XB_IS_SILO(self));

  if (priv->enable_node_cache == enable_node_cache)
    return;

  priv->enable_node_cache = enable_node_cache;

  /* if disabling the cache, destroy any existing data structures;
   * if enabling it, create them lazily when the first entry is cached
   * (see xb_silo_create_node()) */
  if (!enable_node_cache) {
    g_clear_pointer(&priv->nodes, g_hash_table_unref);
  }

  silo_notify(self, obj_props[PROP_ENABLE_NODE_CACHE]);
}

/* private */
XbSiloProfileFlags
xb_silo_get_profile_flags(XbSilo *self)
{
  XbSiloPrivate *priv = GET_PRIVATE(self);
  return priv->profile_flags;
}

/* This will be invoked in silo->context */
static void
xb_silo_watch_file_cb(GFileMonitor *monitor,
          GFile *file,
          GFile *other_file,
          GFileMonitorEvent event_type,
          gpointer user_data)
{
  XbSilo *silo = XB_SILO(user_data);
  g_autofree gchar *fn = g_file_get_path(file);
  g_autofree gchar *basename = g_file_get_basename(file);
  if (g_str_has_prefix(basename, "."))
    return;
  g_debug("%s changed, invalidating", fn);
  xb_silo_invalidate(silo);
}

typedef struct {
  XbSilo *silo; /* (owned) */
  GFile *file;  /* (owned) */
} WatchFileData;

static void
watch_file_data_free(WatchFileData *data)
{
  g_clear_object(&data->silo);
  g_clear_object(&data->file);
  g_free(data);
}

G_DEFINE_AUTOPTR_CLEANUP_FUNC(WatchFileData, watch_file_data_free)

static gboolean
watch_file_cb(gpointer user_data);

/**
 * xb_silo_watch_file:
 * @self: a #XbSilo
 * @file: a #GFile
 * @cancellable: a #GCancellable, or %NULL
 * @error: the #GError, or %NULL
 *
 * Adds a file monitor to the silo. If the file or directory for @file changes
 * then the silo will be invalidated.
 *
 * The monitor will internally use the #GMainContext which was the thread
 * default when the #XbSilo was created, so that #GMainContext must be iterated
 * for monitoring to work.
 *
 * Returns: %TRUE for success, otherwise @error is set.
 *
 * Since: 0.1.0
 **/
gboolean
xb_silo_watch_file(XbSilo *self, GFile *file, GCancellable *cancellable, GError **error)
{
  XbSiloPrivate *priv = GET_PRIVATE(self);
  g_autoptr(WatchFileData) data = NULL;

  g_return_val_if_fail(XB_IS_SILO(self), FALSE);
  g_return_val_if_fail(cancellable == NULL || G_IS_CANCELLABLE(cancellable), FALSE);
  g_return_val_if_fail(error == NULL || *error == NULL, FALSE);

  /* return if cancelled; this is basically the only failure mode of
   * g_file_monitor() for local files, and this function shouldn’t really
   * be called on non-local files */
  if (g_cancellable_set_error_if_cancelled(cancellable, error))
    return FALSE;

  data = g_new0(WatchFileData, 1);
  data->silo = g_object_ref(self);
  data->file = g_object_ref(file);

  g_main_context_invoke(priv->context, watch_file_cb, g_steal_pointer(&data));

  return TRUE;
}

static gboolean
watch_file_cb(gpointer user_data)
{
  g_autoptr(WatchFileData) data = g_steal_pointer(&user_data);
  XbSilo *self = data->silo;
  GFile *file = data->file;
  XbSiloFileMonitorItem *item;
  XbSiloPrivate *priv = GET_PRIVATE(self);
  g_autoptr(GFileMonitor) file_monitor = NULL;
  g_autoptr(GError) error_local = NULL;
  g_autoptr(GMutexLocker) locker = g_mutex_locker_new(&priv->file_monitors_mutex);

  g_return_val_if_fail(locker != NULL, FALSE);

  /* already exists */
  item = g_hash_table_lookup(priv->file_monitors, file);
  if (item != NULL)
    return G_SOURCE_REMOVE;

  /* try to create */
  file_monitor = g_file_monitor(file, G_FILE_MONITOR_NONE, NULL, &error_local);
  if (file_monitor == NULL) {
    g_warning("Error adding file monitor: %s", error_local->message);
    return G_SOURCE_REMOVE;
  }

  g_file_monitor_set_rate_limit(file_monitor, 20);

  /* add */
  item = g_slice_new0(XbSiloFileMonitorItem);
  item->file_monitor = g_object_ref(file_monitor);
  item->file_monitor_id =
      g_signal_connect(file_monitor, "changed", G_CALLBACK(xb_silo_watch_file_cb), self);
  g_hash_table_insert(priv->file_monitors, g_object_ref(file), item);

  return G_SOURCE_REMOVE;
}

/**
 * xb_silo_load_from_file:
 * @self: a #XbSilo
 * @file: a #GFile
 * @flags: #XbSiloLoadFlags, e.g. %XB_SILO_LOAD_FLAG_NONE
 * @cancellable: a #GCancellable, or %NULL
 * @error: the #GError, or %NULL
 *
 * Loads a silo from file.
 *
 * Returns: %TRUE for success, otherwise @error is set.
 *
 * Since: 0.1.0
 **/
gboolean
xb_silo_load_from_file(XbSilo *self,
           GFile *file,
           XbSiloLoadFlags flags,
           GCancellable *cancellable,
           GError **error)
{
  XbSiloPrivate *priv = GET_PRIVATE(self);
  g_autofree gchar *fn = NULL;
  g_autoptr(GBytes) blob = NULL;
  g_autoptr(GTimer) timer = xb_silo_start_profile(self);
  g_autoptr(GMutexLocker) file_monitors_locker =
      g_mutex_locker_new(&priv->file_monitors_mutex);

  g_return_val_if_fail(XB_IS_SILO(self), FALSE);
  g_return_val_if_fail(G_IS_FILE(file), FALSE);
  g_return_val_if_fail(cancellable == NULL || G_IS_CANCELLABLE(cancellable), FALSE);
  g_return_val_if_fail(error == NULL || *error == NULL, FALSE);

  /* no longer valid (@nodes is cleared by xb_silo_load_from_bytes()) */
  g_hash_table_remove_all(priv->file_monitors);
  g_clear_pointer(&file_monitors_locker, g_mutex_locker_free);

  g_hash_table_remove_all(priv->strtab_tags);
  g_clear_pointer(&priv->guid, g_free);
  g_clear_pointer(&priv->mmap, g_mapped_file_unref);

  fn = g_file_get_path(file);
  priv->mmap = g_mapped_file_new(fn, FALSE, error);
  if (priv->mmap == NULL)
    return FALSE;
  blob = g_mapped_file_get_bytes(priv->mmap);
  if (!xb_silo_load_from_bytes(self, blob, flags, error))
    return FALSE;

  /* watch file for changes */
  if (flags & XB_SILO_LOAD_FLAG_WATCH_BLOB) {
    if (!xb_silo_watch_file(self, file, cancellable, error))
      return FALSE;
  }

  /* success */
  xb_silo_add_profile(self, timer, "loaded file");
  return TRUE;
}

/**
 * xb_silo_save_to_file:
 * @self: a #XbSilo
 * @file: a #GFile
 * @cancellable: a #GCancellable, or %NULL
 * @error: the #GError, or %NULL
 *
 * Saves a silo to a file.
 *
 * Returns: %TRUE for success, otherwise @error is set.
 *
 * Since: 0.1.0
 **/
gboolean
xb_silo_save_to_file(XbSilo *self, GFile *file, GCancellable *cancellable, GError **error)
{
  XbSiloPrivate *priv = GET_PRIVATE(self);
  g_autoptr(GFile) file_parent = NULL;
  g_autoptr(GTimer) timer = xb_silo_start_profile(self);

  g_return_val_if_fail(XB_IS_SILO(self), FALSE);
  g_return_val_if_fail(G_IS_FILE(file), FALSE);
  g_return_val_if_fail(cancellable == NULL || G_IS_CANCELLABLE(cancellable), FALSE);
  g_return_val_if_fail(error == NULL || *error == NULL, FALSE);

  /* invalid */
  if (priv->data == NULL) {
    g_set_error_literal(error,
            G_IO_ERROR,
            G_IO_ERROR_NOT_INITIALIZED,
            "no data to save");
    return FALSE;
  }

  /* ensure parent directories exist */
  file_parent = g_file_get_parent(file);
  if (file_parent != NULL && !g_file_query_exists(file_parent, cancellable)) {
    if (!g_file_make_directory_with_parents(file_parent, cancellable, error))
      return FALSE;
  }

  /* save and then rename */
  if (!xb_file_set_contents(file, priv->data, (gsize)priv->datasz, cancellable, error))
    return FALSE;

  xb_silo_add_profile(self, timer, "save file");
  return TRUE;
}

/**
 * xb_silo_new_from_xml:
 * @xml: XML string
 * @error: the #GError, or %NULL
 *
 * Creates a new silo from an XML string.
 *
 * Returns: a new #XbSilo, or %NULL
 *
 * Since: 0.1.0
 **/
XbSilo *
xb_silo_new_from_xml(const gchar *xml, GError **error)
{
  g_autoptr(XbBuilder) builder = xb_builder_new();
  g_autoptr(XbBuilderSource) source = xb_builder_source_new();
  g_return_val_if_fail(xml != NULL, NULL);
  g_return_val_if_fail(error == NULL || *error == NULL, NULL);
  if (!xb_builder_source_load_xml(source, xml, XB_BUILDER_SOURCE_FLAG_NONE, error))
    return NULL;
  xb_builder_import_source(builder, source);
  return xb_builder_compile(builder, XB_BUILDER_COMPILE_FLAG_NONE, NULL, error);
}

/* private */
XbNode *
xb_silo_create_node(XbSilo *self, XbSiloNode *sn, gboolean force_node_cache)
{
  XbNode *n;
  XbSiloPrivate *priv = GET_PRIVATE(self);
  g_autoptr(GMutexLocker) locker = NULL;

  /* the cache should only be enabled/disabled before threads are
   * spawned, so `priv->enable_node_cache` can be accessed unlocked */
  if (!priv->enable_node_cache && !force_node_cache)
    return xb_node_new(self, sn);

  locker = g_mutex_locker_new(&priv->nodes_mutex);

  /* ensure the cache exists */
  if (priv->nodes == NULL)
    priv->nodes = g_hash_table_new_full(g_direct_hash,
                g_direct_equal,
                NULL,
                (GDestroyNotify)g_object_unref);

  /* does already exist */
  n = g_hash_table_lookup(priv->nodes, sn);
  if (n != NULL)
    return g_object_ref(n);

  /* create and add */
  n = xb_node_new(self, sn);
  g_hash_table_insert(priv->nodes, sn, g_object_ref(n));
  return n;
}

/* Push two opcodes onto the stack with appropriate rollback on failure. */
static gboolean
_xb_stack_push_two(XbStack *opcodes, XbOpcode **op1, XbOpcode **op2, GError **error)
{
  if (!xb_stack_push(opcodes, op1, error))
    return FALSE;
  if (!xb_stack_push(opcodes, op2, error)) {
    xb_stack_pop(opcodes, NULL, NULL);
    return FALSE;
  }
  return TRUE;
}

/* convert [2] to position()=2 */
static gboolean
xb_silo_machine_fixup_position_cb(XbMachine *self,
          XbStack *opcodes,
          gpointer user_data,
          GError **error)
{
  XbOpcode *op1;
  XbOpcode *op2;
  XbOpcode *tail = xb_stack_peek_tail(opcodes);

  if (!_xb_stack_push_two(opcodes, &op1, &op2, error))
    return FALSE;

  xb_machine_opcode_func_init(self, op1, "position");
  xb_machine_opcode_func_init(self, op2, "eq");

  /* always exists, but maybe a @level would be cleaner */
  if (tail != NULL) {
    xb_opcode_set_level(op1, _xb_opcode_get_level(tail));
    xb_opcode_set_level(op2, _xb_opcode_get_level(tail));
  }

  return TRUE;
}

/* convert "'type' attr()" -> "'type' attr() '(null)' ne()" */
static gboolean
xb_silo_machine_fixup_attr_exists_cb(XbMachine *self,
             XbStack *opcodes,
             gpointer user_data,
             GError **error)
{
  XbOpcode *op1;
  XbOpcode *op2;
  XbOpcode *tail = xb_stack_peek_tail(opcodes);

  if (!_xb_stack_push_two(opcodes, &op1, &op2, error))
    return FALSE;

  xb_opcode_text_init_static(op1, NULL);
  xb_machine_opcode_func_init(self, op2, "ne");

  /* always exists, but maybe a @level would be cleaner */
  if (tail != NULL) {
    xb_opcode_set_level(op1, _xb_opcode_get_level(tail));
    xb_opcode_set_level(op2, _xb_opcode_get_level(tail));
  }

  return TRUE;
}

static gboolean
xb_silo_machine_fixup_attr_search_token_cb(XbMachine *self,
             XbStack *opcodes,
             gpointer user_data,
             GError **error)
{
  XbOpcode op_func;
  XbOpcode op_text;
  XbOpcode op_search;
  XbOpcode *op_tmp;

  /* text() */
  if (!xb_machine_stack_pop(self, opcodes, &op_func, error))
    return FALSE;

  /* TEXT */
  if (!xb_machine_stack_pop(self, opcodes, &op_text, error))
    return FALSE;
  xb_machine_opcode_tokenize(self, &op_text);

  /* search() */
  if (!xb_machine_stack_pop(self, opcodes, &op_search, error))
    return FALSE;

  /* text() */
  if (!xb_machine_stack_push(self, opcodes, &op_tmp, error))
    return FALSE;
  *op_tmp = op_search;

  /* TEXT */
  if (!xb_machine_stack_push(self, opcodes, &op_tmp, error))
    return FALSE;
  *op_tmp = op_text;

  /* search() */
  if (!xb_machine_stack_push(self, opcodes, &op_tmp, error))
    return FALSE;
  *op_tmp = op_func;
  return TRUE;
}

static gboolean
xb_silo_machine_func_attr_cb(XbMachine *self,
           XbStack *stack,
           gboolean *result,
           gpointer user_data,
           gpointer exec_data,
           GError **error)
{
  XbOpcode *op2;
  XbSiloNodeAttr *a;
  XbSilo *silo = XB_SILO(user_data);
  XbSiloQueryData *query_data = (XbSiloQueryData *)exec_data;
  const gchar *attr_value;
  g_auto(XbOpcode) op = XB_OPCODE_INIT();

  /* optimize pass */
  if (query_data == NULL) {
    g_set_error_literal(error,
            G_IO_ERROR,
            G_IO_ERROR_FAILED_HANDLED,
            "cannot optimize: no silo to query");
    return FALSE;
  }

  if (!xb_machine_stack_pop(self, stack, &op, error))
    return FALSE;

  /* indexed string */
  if (xb_opcode_get_kind(&op) == XB_OPCODE_KIND_INDEXED_TEXT) {
    guint32 val = xb_opcode_get_val(&op);
    a = xb_silo_node_get_attr_by_val(silo, query_data->sn, val);
  } else {
    const gchar *str = xb_opcode_get_str(&op);
    a = xb_silo_get_node_attr_by_str(silo, query_data->sn, str);
  }
  if (a == NULL) {
    return xb_machine_stack_push_text_static(self, stack, NULL, error);
  }
  if (!xb_machine_stack_push(self, stack, &op2, error))
    return FALSE;
  attr_value = xb_silo_from_strtab(silo, a->attr_value, error);
  if (attr_value == NULL)
    return FALSE;
  xb_opcode_init(op2, XB_OPCODE_KIND_INDEXED_TEXT, attr_value, a->attr_value, NULL);
  return TRUE;
}

static gboolean
xb_silo_machine_func_stem_cb(XbMachine *self,
           XbStack *stack,
           gboolean *result,
           gpointer user_data,
           gpointer exec_data,
           GError **error)
{
  XbSilo *silo = XB_SILO(user_data);
  XbOpcode *head;
  const gchar *str;
  g_auto(XbOpcode) op = XB_OPCODE_INIT();

  head = xb_stack_peek_head(stack);
  if (head == NULL || !xb_opcode_cmp_str(head)) {
    g_set_error(error,
          G_IO_ERROR,
          G_IO_ERROR_NOT_SUPPORTED,
          "%s type not supported",
          (head != NULL) ? xb_opcode_kind_to_string(xb_opcode_get_kind(head))
             : "(null)");
    return FALSE;
  }

  if (!xb_machine_stack_pop(self, stack, &op, error))
    return FALSE;

  /* TEXT */
  str = xb_opcode_get_str(&op);
  return xb_machine_stack_push_text_steal(self, stack, xb_silo_stem(silo, str), error);
}

static gboolean
xb_silo_machine_func_text_cb(XbMachine *self,
           XbStack *stack,
           gboolean *result,
           gpointer user_data,
           gpointer exec_data,
           GError **error)
{
  XbSilo *silo = XB_SILO(user_data);
  XbSiloQueryData *query_data = (XbSiloQueryData *)exec_data;
  XbOpcode *op;
  const gchar *text;
  guint8 token_count;

  /* optimize pass */
  if (query_data == NULL) {
    g_set_error_literal(error,
            G_IO_ERROR,
            G_IO_ERROR_FAILED_HANDLED,
            "cannot optimize: no silo to query");
    return FALSE;
  }

  if (xb_silo_node_get_text_idx(query_data->sn) != XB_SILO_UNSET) {
    text = xb_silo_from_strtab(silo, xb_silo_node_get_text_idx(query_data->sn), error);
    if (text == NULL)
      return FALSE;
  } else {
    text = "";
  }
  if (!xb_machine_stack_push(self, stack, &op, error))
    return FALSE;
  xb_opcode_init(op,
           XB_OPCODE_KIND_INDEXED_TEXT,
           text,
           xb_silo_node_get_text_idx(query_data->sn),
           NULL);

  /* use the fast token path even if there are no valid tokens */
  if (xb_silo_node_has_flag(query_data->sn, XB_SILO_NODE_FLAG_IS_TOKENIZED))
    xb_opcode_add_flag(op, XB_OPCODE_FLAG_TOKENIZED);

  /* add tokens */
  token_count = xb_silo_node_get_token_count(query_data->sn);
  for (guint i = 0; i < token_count; i++) {
    guint32 stridx = xb_silo_node_get_token_idx(query_data->sn, i);
    const gchar *token = xb_silo_from_strtab(silo, stridx, error);
    if (token == NULL)
      return FALSE;
    xb_opcode_append_token(op, token);
  }

  return TRUE;
}

static gboolean
xb_silo_machine_func_tail_cb(XbMachine *self,
           XbStack *stack,
           gboolean *result,
           gpointer user_data,
           gpointer exec_data,
           GError **error)
{
  XbSilo *silo = XB_SILO(user_data);
  XbSiloQueryData *query_data = (XbSiloQueryData *)exec_data;
  const gchar *tail;
  XbOpcode *op;

  /* optimize pass */
  if (query_data == NULL) {
    g_set_error_literal(error,
            G_IO_ERROR,
            G_IO_ERROR_FAILED_HANDLED,
            "cannot optimize: no silo to query");
    return FALSE;
  }

  if (xb_silo_node_get_tail_idx(query_data->sn) != XB_SILO_UNSET) {
    tail = xb_silo_from_strtab(silo, xb_silo_node_get_tail_idx(query_data->sn), error);
    if (tail == NULL)
      return FALSE;
  } else {
    tail = "";
  }
  if (!xb_machine_stack_push(self, stack, &op, error))
    return FALSE;
  xb_opcode_init(op,
           XB_OPCODE_KIND_INDEXED_TEXT,
           tail,
           xb_silo_node_get_tail_idx(query_data->sn),
           NULL);
  return TRUE;
}

static gboolean
xb_silo_machine_func_first_cb(XbMachine *self,
            XbStack *stack,
            gboolean *result,
            gpointer user_data,
            gpointer exec_data,
            GError **error)
{
  XbSiloQueryData *query_data = (XbSiloQueryData *)exec_data;

  /* optimize pass */
  if (query_data == NULL) {
    g_set_error_literal(error,
            G_IO_ERROR,
            G_IO_ERROR_FAILED_HANDLED,
            "cannot optimize: no silo to query");
    return FALSE;
  }
  return xb_stack_push_bool(stack, query_data->position == 1, error);
}

static gboolean
xb_silo_machine_func_last_cb(XbMachine *self,
           XbStack *stack,
           gboolean *result,
           gpointer user_data,
           gpointer exec_data,
           GError **error)
{
  XbSiloQueryData *query_data = (XbSiloQueryData *)exec_data;

  /* optimize pass */
  if (query_data == NULL) {
    g_set_error_literal(error,
            G_IO_ERROR,
            G_IO_ERROR_FAILED_HANDLED,
            "cannot optimize: no silo to query");
    return FALSE;
  }
  return xb_stack_push_bool(stack, query_data->sn->next == 0, error);
}

static gboolean
xb_silo_machine_func_position_cb(XbMachine *self,
         XbStack *stack,
         gboolean *result,
         gpointer user_data,
         gpointer exec_data,
         GError **error)
{
  XbSiloQueryData *query_data = (XbSiloQueryData *)exec_data;

  /* optimize pass */
  if (query_data == NULL) {
    g_set_error_literal(error,
            G_IO_ERROR,
            G_IO_ERROR_FAILED_HANDLED,
            "cannot optimize: no silo to query");
    return FALSE;
  }
  return xb_machine_stack_push_integer(self, stack, query_data->position, error);
}

static gboolean
xb_silo_machine_func_search_cb(XbMachine *self,
             XbStack *stack,
             gboolean *result,
             gpointer user_data,
             gpointer exec_data,
             GError **error)
{
  XbSilo *silo = XB_SILO(user_data);
  XbSiloPrivate *priv = GET_PRIVATE(silo);
  const gchar *text;
  const gchar *search;
  XbOpcode *head1 = NULL;
  XbOpcode *head2 = NULL;
  g_auto(XbOpcode) op1 = XB_OPCODE_INIT();
  g_auto(XbOpcode) op2 = XB_OPCODE_INIT();

  if (xb_stack_get_size(stack) >= 2) {
    head1 = xb_stack_peek(stack, xb_stack_get_size(stack) - 1);
    head2 = xb_stack_peek(stack, xb_stack_get_size(stack) - 2);
  }
  if (head1 == NULL || !xb_opcode_cmp_str(head1) || head2 == NULL ||
      !xb_opcode_cmp_str(head2)) {
    g_set_error(error,
          G_IO_ERROR,
          G_IO_ERROR_NOT_SUPPORTED,
          "%s:%s types not supported",
          (head1 != NULL) ? xb_opcode_kind_to_string(xb_opcode_get_kind(head1))
              : "(null)",
          (head2 != NULL) ? xb_opcode_kind_to_string(xb_opcode_get_kind(head2))
              : "(null)");
    return FALSE;
  }

  if (!xb_machine_stack_pop_two(self, stack, &op1, &op2, error))
    return FALSE;

  /* this cannot be optimized away when constructing the query */
  if (!_xb_opcode_has_flag(&op1, XB_OPCODE_FLAG_TOKENIZED) &&
      _xb_opcode_get_kind(&op1) == XB_OPCODE_KIND_BOUND_TEXT) {
    xb_machine_opcode_tokenize(self, &op1);
  }
  if (!_xb_opcode_has_flag(&op2, XB_OPCODE_FLAG_TOKENIZED) &&
      _xb_opcode_get_kind(&op2) == XB_OPCODE_KIND_BOUND_TEXT) {
    xb_machine_opcode_tokenize(self, &op2);
  }

  /* TOKN:TOKN */
  if (xb_opcode_has_flag(&op1, XB_OPCODE_FLAG_TOKENIZED) &&
      xb_opcode_has_flag(&op2, XB_OPCODE_FLAG_TOKENIZED)) {
    return xb_stack_push_bool(
        stack,
        xb_string_searchv(xb_opcode_get_tokens(&op2), xb_opcode_get_tokens(&op1)),
        error);
  }

  /* this is going to be slow, but correct */
  text = xb_opcode_get_str(&op2);
  search = xb_opcode_get_str(&op1);
  if (text == NULL || search == NULL || text[0] == '\0' || search[0] == '\0')
    return xb_stack_push_bool(stack, FALSE, error);
  if (!g_str_is_ascii(text) || !g_str_is_ascii(search)) {
    if (priv->profile_flags & XB_SILO_PROFILE_FLAG_DEBUG) {
      g_debug("tokenization for [%s:%s] may be slow!", text, search);
    }
    return xb_stack_push_bool(stack, g_str_match_string(search, text, TRUE), error);
  }

  /* TEXT:TEXT */
  return xb_stack_push_bool(stack, xb_string_search(text, search), error);
}

static gboolean
xb_silo_machine_fixup_attr_text_cb(XbMachine *self,
           XbStack *opcodes,
           const gchar *text,
           gboolean *handled,
           gpointer user_data,
           GError **error)
{
  /* @foo -> attr(foo) */
  if (g_str_has_prefix(text, "@")) {
    XbOpcode *op1;
    XbOpcode *op2;

    if (!_xb_stack_push_two(opcodes, &op1, &op2, error))
      return FALSE;

    xb_opcode_text_init(op1, text + 1);
    if (!xb_machine_opcode_func_init(self, op2, "attr")) {
      g_set_error_literal(error,
              G_IO_ERROR,
              G_IO_ERROR_NOT_SUPPORTED,
              "no attr opcode");
      xb_stack_pop(opcodes, NULL, NULL);
      xb_stack_pop(opcodes, NULL, NULL);
      return FALSE;
    }

    *handled = TRUE;
    return TRUE;
  }

  /* not us */
  return TRUE;
}

static void
xb_silo_file_monitor_item_free(XbSiloFileMonitorItem *item)
{
  g_file_monitor_cancel(item->file_monitor);
  g_signal_handler_disconnect(item->file_monitor, item->file_monitor_id);
  g_object_unref(item->file_monitor);
  g_slice_free(XbSiloFileMonitorItem, item);
}

static void
xb_silo_get_property(GObject *obj, guint prop_id, GValue *value, GParamSpec *pspec)
{
  XbSilo *self = XB_SILO(obj);
  XbSiloPrivate *priv = GET_PRIVATE(self);
  switch ((XbSiloProperty)prop_id) {
  case PROP_GUID:
    g_value_set_string(value, priv->guid);
    break;
  case PROP_VALID:
    g_value_set_boolean(value, priv->valid);
    break;
  case PROP_ENABLE_NODE_CACHE:
    g_value_set_boolean(value, priv->enable_node_cache);
    break;
  default:
    G_OBJECT_WARN_INVALID_PROPERTY_ID(obj, prop_id, pspec);
    break;
  }
}

static void
xb_silo_set_property(GObject *obj, guint prop_id, const GValue *value, GParamSpec *pspec)
{
  XbSilo *self = XB_SILO(obj);
  XbSiloPrivate *priv = GET_PRIVATE(self);
  switch ((XbSiloProperty)prop_id) {
  case PROP_GUID:
    g_free(priv->guid);
    priv->guid = g_value_dup_string(value);
    silo_notify(self, obj_props[PROP_GUID]);
    break;
  case PROP_VALID:
    /* Read only */
    g_assert_not_reached();
    break;
  case PROP_ENABLE_NODE_CACHE:
    xb_silo_set_enable_node_cache(self, g_value_get_boolean(value));
    break;
  default:
    G_OBJECT_WARN_INVALID_PROPERTY_ID(obj, prop_id, pspec);
    break;
  }
}

static void
xb_silo_init(XbSilo *self)
{
  XbSiloPrivate *priv = GET_PRIVATE(self);

  priv->file_monitors = g_hash_table_new_full(g_file_hash,
                (GEqualFunc)g_file_equal,
                g_object_unref,
                (GDestroyNotify)xb_silo_file_monitor_item_free);
  g_mutex_init(&priv->file_monitors_mutex);

  priv->strtab_tags = g_hash_table_new(g_str_hash, g_str_equal);
  priv->strindex = g_hash_table_new(g_str_hash, g_str_equal);
  priv->profile_str = g_string_new(NULL);
  priv->query_cache = g_hash_table_new_full(g_str_hash, g_str_equal, g_free, g_object_unref);
  g_rw_lock_init(&priv->query_cache_mutex);

  priv->nodes = NULL; /* initialised when first used */
  g_mutex_init(&priv->nodes_mutex);

  priv->context = g_main_context_ref_thread_default();

#ifdef HAVE_LIBSTEMMER
  g_mutex_init(&priv->stemmer_mutex);
#endif

  priv->machine = xb_machine_new();
  xb_machine_add_method(priv->machine, "attr", 1, xb_silo_machine_func_attr_cb, self, NULL);
  xb_machine_add_method(priv->machine, "stem", 1, xb_silo_machine_func_stem_cb, self, NULL);
  xb_machine_add_method(priv->machine, "text", 0, xb_silo_machine_func_text_cb, self, NULL);
  xb_machine_add_method(priv->machine, "tail", 0, xb_silo_machine_func_tail_cb, self, NULL);
  xb_machine_add_method(priv->machine, "first", 0, xb_silo_machine_func_first_cb, self, NULL);
  xb_machine_add_method(priv->machine, "last", 0, xb_silo_machine_func_last_cb, self, NULL);
  xb_machine_add_method(priv->machine,
            "position",
            0,
            xb_silo_machine_func_position_cb,
            self,
            NULL);
  xb_machine_add_method(priv->machine,
            "search",
            2,
            xb_silo_machine_func_search_cb,
            self,
            NULL);
  xb_machine_add_operator(priv->machine, "~=", "search");
  xb_machine_add_opcode_fixup(priv->machine,
            "INTE",
            xb_silo_machine_fixup_position_cb,
            self,
            NULL);
  xb_machine_add_opcode_fixup(priv->machine,
            "TEXT,FUNC:attr",
            xb_silo_machine_fixup_attr_exists_cb,
            self,
            NULL);
  xb_machine_add_opcode_fixup(priv->machine,
            "FUNC:text,TEXT,FUNC:search",
            xb_silo_machine_fixup_attr_search_token_cb,
            self,
            NULL);
  xb_machine_add_text_handler(priv->machine, xb_silo_machine_fixup_attr_text_cb, self, NULL);
}

static void
xb_silo_finalize(GObject *obj)
{
  XbSilo *self = XB_SILO(obj);
  XbSiloPrivate *priv = GET_PRIVATE(self);

  g_clear_pointer(&priv->nodes, g_hash_table_unref);
  g_mutex_clear(&priv->nodes_mutex);

#ifdef HAVE_LIBSTEMMER
  if (priv->stemmer_ctx != NULL)
    sb_stemmer_delete(priv->stemmer_ctx);
  g_mutex_clear(&priv->stemmer_mutex);
#endif

  g_clear_pointer(&priv->context, g_main_context_unref);

  g_free(priv->guid);
  g_string_free(priv->profile_str, TRUE);
  g_hash_table_unref(priv->query_cache);
  g_rw_lock_clear(&priv->query_cache_mutex);
  g_object_unref(priv->machine);
  g_hash_table_unref(priv->strindex);
  g_hash_table_unref(priv->file_monitors);
  g_mutex_clear(&priv->file_monitors_mutex);
  g_hash_table_unref(priv->strtab_tags);
  if (priv->mmap != NULL)
    g_mapped_file_unref(priv->mmap);
  if (priv->blob != NULL)
    g_bytes_unref(priv->blob);
  G_OBJECT_CLASS(xb_silo_parent_class)->finalize(obj);
}

static void
xb_silo_class_init(XbSiloClass *klass)
{
  GObjectClass *object_class = G_OBJECT_CLASS(klass);
  object_class->finalize = xb_silo_finalize;
  object_class->get_property = xb_silo_get_property;
  object_class->set_property = xb_silo_set_property;

  /**
   * XbSilo:guid:
   */
  obj_props[PROP_GUID] =
      g_param_spec_string("guid",
        NULL,
        NULL,
        NULL,
        G_PARAM_READWRITE | G_PARAM_CONSTRUCT | G_PARAM_STATIC_STRINGS |
            G_PARAM_EXPLICIT_NOTIFY);

  /**
   * XbSilo:valid:
   */
  obj_props[PROP_VALID] = g_param_spec_boolean("valid",
                 NULL,
                 NULL,
                 TRUE,
                 G_PARAM_READABLE | G_PARAM_STATIC_STRINGS |
               G_PARAM_EXPLICIT_NOTIFY);

  /**
   * XbSilo:enable-node-cache:
   *
   * Whether to cache all #XbNode instances ever constructed in a single
   * cache in the #XbSilo, so that the same #XbNode instance is always
   * returned in query results for a given XPath. This is a form of
   * memoisation, and allows xb_node_get_data() and xb_node_set_data() to
   * be used.
   *
   * This is enabled by default to preserve compatibility with older
   * versions of libxmlb, but most clients will want to disable it. It
   * adds a large memory overhead (no #XbNode is ever finalised) but
   * achieves moderately low hit rates for typical XML parsing workloads
   * where most nodes are accessed only once or twice as they are
   * processed and then processing moves on to other nodes.
   *
   * This property can only be changed before the #XbSilo is passed
   * between threads. Changing it is not thread-safe.
   *
   * Since: 0.2.0
   */
  obj_props[PROP_ENABLE_NODE_CACHE] = g_param_spec_boolean(
      "enable-node-cache",
      NULL,
      NULL,
      TRUE,
      G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS | G_PARAM_EXPLICIT_NOTIFY);

  g_object_class_install_properties(object_class, G_N_ELEMENTS(obj_props), obj_props);
}

/**
 * xb_silo_new:
 *
 * Creates a new silo.
 *
 * Returns: a new #XbSilo
 *
 * Since: 0.1.0
 **/
XbSilo *
xb_silo_new(void)
{
  return g_object_new(XB_TYPE_SILO, NULL);
}

/**
 * xb_silo_lookup_query:
 * @self: an #XbSilo
 * @xpath: an XPath query string
 *
 * Create an #XbQuery from the given @xpath XPath string, or return it from the
 * query cache in the #XbSilo.
 *
 * @xpath must be valid: it is a programmer error if creating the query fails
 * (i.e. if xb_query_new() returns an error).
 *
 * This function is thread-safe.
 *
 * Returns: (transfer full): an #XbQuery representing @xpath
 * Since: 0.3.0
 */
XbQuery *
xb_silo_lookup_query(XbSilo *self, const gchar *xpath)
{
  XbSiloPrivate *priv = GET_PRIVATE(self);
  XbQuery *result;

  g_rw_lock_reader_lock(&priv->query_cache_mutex);
  result = g_hash_table_lookup(priv->query_cache, xpath);
  g_rw_lock_reader_unlock(&priv->query_cache_mutex);

  if (result != NULL) {
    g_object_ref(result);
  } else {
    g_autoptr(XbQuery) query = NULL;

    /* check again with an exclusive lock */
    g_rw_lock_writer_lock(&priv->query_cache_mutex);
    result = g_hash_table_lookup(priv->query_cache, xpath);
    if (result != NULL) {
      g_object_ref(result);
    } else {
      g_autoptr(GError) error_local = NULL;

      query = xb_query_new(self, xpath, &error_local);
      if (query == NULL) {
        /* This should not happen: the caller should
         * have written a valid query. */
        g_error("Invalid XPath query ‘%s’: %s",
          xpath,
          error_local->message);
        g_rw_lock_writer_unlock(&priv->query_cache_mutex);
        g_assert_not_reached();
        return NULL;
      }

      result = g_object_ref(query);

      g_hash_table_insert(priv->query_cache,
              g_strdup(xpath),
              g_steal_pointer(&query));
      g_debug(
          "Caching query ‘%s’ (%p) in silo %p; query cache now has %u entries",
          xpath,
          query,
          self,
          g_hash_table_size(priv->query_cache));
    }
    g_rw_lock_writer_unlock(&priv->query_cache_mutex);
  }

  return result;
}

Coverage Report

Created: 2025-07-18 06:26