/*

  Copyright (c) 1998-2018 University Corporation for Atmospheric Research/Unidata

  See LICENSE.txt for license information.

*/

/** \file \internal

    Internal netcdf-4 functions.

    This file contains functions for manipulating NCxcache objects.

    Warning: This code depends critically on the assumption that

    |void*| == |uintptr_t|

*/

/* 0 => no debug */

#define DEBUG 0

#define CATCH

/* Define this for debug so that table sizes are small */

#define SMALLTABLE

#ifdef CATCH

#define THROW(x) throw(x)

static void breakpoint(void) {}

static int ignore[] = {0};

static int throw(int x)

{

    int* p;

    if(x != 0) {

  for(p=ignore;*p;p++) {if(x == *p) break;}

  if(*p == 0) breakpoint();

    }

    return x;

}

#else

#define THROW(x) (x)

#endif

#include "config.h"

#include <stdlib.h>

#include <stdio.h>

#include <string.h>

#ifdef HAVE_STDINT_H

#include <stdint.h>

#endif

#include <assert.h>

#include "nc4internal.h"

#include "ncexhash.h"

#include "ncxcache.h"

#ifdef SMALLTABLE

/* Keep the table sizes small initially */

#define DFALTTABLESIZE 4

#define DFALTLEAFLEN 4

#else

#define DFALTTABLESIZE 32

#define DFALTLEAFLEN 12

#endif

static void insertafter(NCxnode* current, NCxnode* node);

static void unlinknode(NCxnode* node);

#if DEBUG > 0

void verifylru(NCxcache* cache);

static void

xverify(NCxcache* cache)

{

    verifylru(cache);

}

void

verifylru(NCxcache* cache)

{

    NCxnode* p;

    for(p=cache->lru.next;p != &cache->lru;p=p->next) {

        if(p->next == NULL || p->prev == NULL) {

      xverify(cache);

  }

    }

}

#endif

/* Locate object by hashkey in an NCxcache */

int

ncxcachelookup(NCxcache* NCxcache, ncexhashkey_t hkey, void** op)

{

    int stat = NC_NOERR;

    uintptr_t inode = 0;

    NCxnode* node = NULL;

    if(NCxcache == NULL) return THROW(NC_EINVAL);

    assert(NCxcache->map != NULL);

    if((stat=ncexhashget(NCxcache->map,hkey,&inode)))

        {stat = THROW(NC_ENOOBJECT); goto done;} /* not present */

    node = (void*)inode;

    if(op) *op = node->content;

done:

    return stat;

}

/* Move object to the front of the LRU list */

int

ncxcachetouch(NCxcache* cache, ncexhashkey_t hkey)

{

    int stat = NC_NOERR;

    uintptr_t inode = 0;

    NCxnode* node = NULL;

    if(cache == NULL) return THROW(NC_EINVAL);

    if((stat=ncexhashget(cache->map,hkey,&inode)))

        {stat = THROW(NC_ENOOBJECT); goto done;} /* not present */

    node = (void*)inode;

    /* unlink */

    unlinknode(node);

    /* Relink into front of chain */

    insertafter(&cache->lru,node);

#if DEBUG > 0

verifylru(cache);

#endif

done:

    return stat;

}

/* Add object to the cache */

int

ncxcacheinsert(NCxcache* cache, const ncexhashkey_t hkey, void* o)

{

    int stat = NC_NOERR;

    uintptr_t inode = 0;

    NCxnode* node = NULL;

    if(cache == NULL) return THROW(NC_EINVAL);

#ifndef NCXUSER

    node = calloc(1,sizeof(NCxnode));

#else

    node = (NCxnode*)o;

#endif

    node->content = o; /* Cheat and make content point to the node part*/

    inode = (uintptr_t)node;

    stat = ncexhashput(cache->map,hkey,inode);

    if(stat)

  goto done;

    /* link into the LRU chain at front */

    insertafter(&cache->lru,node);

#if DEBUG > 0

verifylru(cache);

#endif

    node = NULL;

done:

#ifndef NCXUSER

    if(node) nullfree(node);

#endif

    return THROW(stat);

}

/* Remove object from the index;*/

int

ncxcacheremove(NCxcache* cache, ncexhashkey_t hkey, void** op)

{

    int stat = NC_NOERR;

    uintptr_t inode = 0;

    NCxnode* node = NULL;

    if(cache == NULL) return THROW(NC_EINVAL);

    /* Remove from the hash map */

    if((stat=ncexhashremove(cache->map,hkey,&inode)))

        {stat = NC_ENOOBJECT; goto done;} /* not present */

    node = (NCxnode*)inode;

    /* unlink */

    unlinknode(node);

#if DEBUG > 0

verifylru(cache);

#endif

    if(op) {

        *op = node->content;

    }

#ifndef NCXUSER

    nullfree(node);

#endif

done:

    return THROW(stat);

}

/* Free a cache */

void

ncxcachefree(NCxcache* cache)

{

    NCxnode* lru = NULL;

    if(cache == NULL) return;

    lru = &cache->lru;

#ifndef NCXUSER

    {

    NCxnode* p = NULL;

    NCxnode* next = NULL;

    /* walk the lru chain */

    next = NULL;

    for(p=lru->next;p != lru;) {

  next = p->next;

  nullfree(p);

  p = next;

    }

    }

#endif

    lru->next = (lru->prev = lru); /*reset*/

    ncexhashmapfree(cache->map);

    free(cache);

}

/* Create a new cache holding at least size objects */

int

ncxcachenew(size_t leaflen, NCxcache** cachep)

{

    int stat = NC_NOERR;

    NCxcache* cache = NULL;

    if(leaflen == 0) leaflen = DFALTLEAFLEN;

    cache = calloc(1,sizeof(NCxcache));

    if(cache == NULL)

        {stat = NC_ENOMEM; goto done;}

    cache->map = ncexhashnew(leaflen);

    if(cache->map == NULL)

        {stat = NC_ENOMEM; goto done;}

    cache->lru.next = &cache->lru;

    cache->lru.prev = &cache->lru;

    if(cachep) {*cachep = cache; cache = NULL;}

done:

    ncxcachefree(cache);

    return THROW(stat);

}

void

ncxcacheprint(NCxcache* cache)

{

    int i;

    NCxnode* p = NULL;

    fprintf(stderr,"NCxcache: lru=");

    fprintf(stderr,"{");

    for(i=0,p=cache->lru.next;p != &cache->lru;p=p->next,i++) {

  if(i>0) fprintf(stderr,",");

  fprintf(stderr,"%p:%p",p,p->content);

    }

    fprintf(stderr,"}\n");

    ncexhashprint(cache->map);

}

void*

ncxcachefirst(NCxcache* cache)

{

    if(cache == NULL) return NULL;

    if(ncexhashcount(cache->map) == 0)

        return NULL;

    return cache->lru.next->content;

}

void*

ncxcachelast(NCxcache* cache)

{

    if(cache == NULL) return NULL;

    if(ncexhashcount(cache->map) == 0)

        return NULL;

    return cache->lru.prev->content;

}

/* Insert node after current */

static void

insertafter(NCxnode* current, NCxnode* node)

{

    NCxnode* curnext = current->next;

    current->next = node;

    node->prev = current;

    node->next = curnext;

    curnext->prev = node;

}

/* Remove node from chain */

static void

unlinknode(NCxnode* node)

{

    NCxnode* next;

    NCxnode* prev;

    assert(node != NULL);

    next = node->next;

    prev = node->prev;

    /* repair the chain */

    next->prev = prev;

    prev->next = next;

    node->next = node->prev = NULL;

}

ncexhashkey_t

ncxcachekey(const void* key, size_t size)

{

    return ncexhashkey((unsigned char*)key,size);

}