/*

 * Copyright (C) 2008 Linus Torvalds

 */

#include "git-compat-util.h"

#include "pathspec.h"

#include "dir.h"

#include "environment.h"

#include "fsmonitor.h"

#include "gettext.h"

#include "parse.h"

#include "preload-index.h"

#include "progress.h"

#include "read-cache.h"

#include "thread-utils.h"

#include "repository.h"

#include "symlinks.h"

#include "trace2.h"

/*

 * Mostly randomly chosen maximum thread counts: we

 * cap the parallelism to 20 threads, and we want

 * to have at least 500 lstat's per thread for it to

 * be worth starting a thread.

 */

#define MAX_PARALLEL (20)

#define THREAD_COST (500)

struct progress_data {

  unsigned long n;

  struct progress *progress;

  pthread_mutex_t mutex;

};

struct thread_data {

  pthread_t pthread;

  struct index_state *index;

  struct pathspec pathspec;

  struct progress_data *progress;

  int offset, nr;

  int t2_nr_lstat;

};

static void *preload_thread(void *_data)

{

  int nr, last_nr;

  struct thread_data *p = _data;

  struct index_state *index = p->index;

  struct cache_entry **cep = index->cache + p->offset;

  struct cache_def cache = CACHE_DEF_INIT;

  nr = p->nr;

  if (nr + p->offset > index->cache_nr)

    nr = index->cache_nr - p->offset;

  last_nr = nr;

  do {

    struct cache_entry *ce = *cep++;

    struct stat st;

    if (ce_stage(ce))

      continue;

    if (S_ISGITLINK(ce->ce_mode))

      continue;

    if (ce_uptodate(ce))

      continue;

    if (ce_skip_worktree(ce))

      continue;

    if (ce->ce_flags & CE_FSMONITOR_VALID)

      continue;

    if (p->progress && !(nr & 31)) {

      struct progress_data *pd = p->progress;

      pthread_mutex_lock(&pd->mutex);

      pd->n += last_nr - nr;

      display_progress(pd->progress, pd->n);

      pthread_mutex_unlock(&pd->mutex);

      last_nr = nr;

    }

    if (!ce_path_match(index, ce, &p->pathspec, NULL))

      continue;

    if (threaded_has_symlink_leading_path(&cache, ce->name, ce_namelen(ce)))

      continue;

    p->t2_nr_lstat++;

    if (lstat(ce->name, &st))

      continue;

    if (ie_match_stat(index, ce, &st, CE_MATCH_RACY_IS_DIRTY|CE_MATCH_IGNORE_FSMONITOR))

      continue;

    ce_mark_uptodate(ce);

    mark_fsmonitor_valid(index, ce);

  } while (--nr > 0);

  if (p->progress) {

    struct progress_data *pd = p->progress;

    pthread_mutex_lock(&pd->mutex);

    display_progress(pd->progress, pd->n + last_nr);

    pthread_mutex_unlock(&pd->mutex);

  }

  cache_def_clear(&cache);

  return NULL;

}

void preload_index(struct index_state *index,

       const struct pathspec *pathspec,

       unsigned int refresh_flags)

{

  int threads, i, work, offset;

  struct thread_data data[MAX_PARALLEL];

  struct progress_data pd;

  int t2_sum_lstat = 0;

  if (!HAVE_THREADS || !core_preload_index)

    return;

  threads = index->cache_nr / THREAD_COST;

  if ((index->cache_nr > 1) && (threads < 2) && git_env_bool("GIT_TEST_PRELOAD_INDEX", 0))

    threads = 2;

  if (threads < 2)

    return;

  trace2_region_enter("index", "preload", NULL);

  trace_performance_enter();

  if (threads > MAX_PARALLEL)

    threads = MAX_PARALLEL;

  offset = 0;

  work = DIV_ROUND_UP(index->cache_nr, threads);

  memset(&data, 0, sizeof(data));

  memset(&pd, 0, sizeof(pd));

  if (refresh_flags & REFRESH_PROGRESS && isatty(2)) {

    pd.progress = start_delayed_progress(_("Refreshing index"), index->cache_nr);

    pthread_mutex_init(&pd.mutex, NULL);

  }

  for (i = 0; i < threads; i++) {

    struct thread_data *p = data+i;

    int err;

    p->index = index;

    if (pathspec)

      copy_pathspec(&p->pathspec, pathspec);

    p->offset = offset;

    p->nr = work;

    if (pd.progress)

      p->progress = &pd;

    offset += work;

    err = pthread_create(&p->pthread, NULL, preload_thread, p);

    if (err)

      die(_("unable to create threaded lstat: %s"), strerror(err));

  }

  for (i = 0; i < threads; i++) {

    struct thread_data *p = data+i;

    if (pthread_join(p->pthread, NULL))

      die("unable to join threaded lstat");

    t2_sum_lstat += p->t2_nr_lstat;

  }

  stop_progress(&pd.progress);

  if (pathspec) {

    /* earlier we made deep copies for each thread to work with */

    for (i = 0; i < threads; i++)

      clear_pathspec(&data[i].pathspec);

  }

  trace_performance_leave("preload index");

  trace2_data_intmax("index", NULL, "preload/sum_lstat", t2_sum_lstat);

  trace2_region_leave("index", "preload", NULL);

}

int repo_read_index_preload(struct repository *repo,

          const struct pathspec *pathspec,

          unsigned int refresh_flags)

{

  int retval = repo_read_index(repo);

  preload_index(repo->index, pathspec, refresh_flags);

  return retval;

}