/* -*- Mode: C; tab-width: 8; indent-tabs-mode: t; c-basic-offset: 8 -*-
*
* Copyright (C) 2000 Helix Code, Inc.
*
* Authors: Michael Zucchi <notzed@helixcode.com>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public License
* as published by the Free Software Foundation; either version 2 of
* the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with the Gnome Library; see the file COPYING.LIB. If not,
* write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
/*
block file/cache/utility functions
*/
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <glib.h>
#include "block.h"
#define d(x)
/*#define DEBUG*/
int block_log;
#ifdef IBEX_STATS
static void
init_stats(struct _memcache *index)
{
index->stats = g_hash_table_new(g_direct_hash, g_direct_equal);
}
static void
dump_1_stat(int id, struct _stat_info *info, struct _memcache *index)
{
printf("%d %d %d %d %d\n", id, info->read, info->write, info->cache_hit, info->cache_miss);
}
static void
dump_stats(struct _memcache *index)
{
printf("Block reads writes hits misses\n");
g_hash_table_foreach(index->stats, dump_1_stat, index);
}
static void
add_read(struct _memcache *index, int id)
{
struct _stat_info *info;
info = g_hash_table_lookup(index->stats, (void *)id);
if (info == NULL) {
info = g_malloc0(sizeof(*info));
g_hash_table_insert(index->stats, (void *)id, info);
}
info->read++;
}
static void
add_write(struct _memcache *index, int id)
{
struct _stat_info *info;
info = g_hash_table_lookup(index->stats, (void *)id);
if (info == NULL) {
info = g_malloc0(sizeof(*info));
g_hash_table_insert(index->stats, (void *)id, info);
}
info->write++;
}
static void
add_hit(struct _memcache *index, int id)
{
struct _stat_info *info;
info = g_hash_table_lookup(index->stats, (void *)id);
if (info == NULL) {
info = g_malloc0(sizeof(*info));
g_hash_table_insert(index->stats, (void *)id, info);
}
info->cache_hit++;
}
static void
add_miss(struct _memcache *index, int id)
{
struct _stat_info *info;
info = g_hash_table_lookup(index->stats, (void *)id);
if (info == NULL) {
info = g_malloc0(sizeof(*info));
g_hash_table_insert(index->stats, (void *)id, info);
}
info->cache_miss++;
}
#endif /* IBEX_STATS */
/* simple list routines (for simplified memory management of cache/lists) */
/**
* ibex_list_new:
* @v:
*
* Initialise a list header. A list header must always be initialised
* before use.
**/
void ibex_list_new(struct _list *v)
{
v->head = (struct _listnode *)&v->tail;
v->tail = 0;
v->tailpred = (struct _listnode *)&v->head;
}
/**
* ibex_list_addhead:
* @l: List.
* @n: Node to append.
*
* Prepend a listnode to the head of the list @l.
*
* Return value: Always @n.
**/
struct _listnode *ibex_list_addhead(struct _list *l, struct _listnode *n)
{
n->next = l->head;
n->prev = (struct _listnode *)&l->head;
l->head->prev = n;
l->head = n;
return n;
}
/**
* ibex_list_addtail:
* @l:
* @n:
*
* Append a listnode to the end of the list @l.
*
* Return value: Always the same as @n.
**/
struct _listnode *ibex_list_addtail(struct _list *l, struct _listnode *n)
{
n->next = (struct _listnode *)&l->tail;
n->prev = l->tailpred;
l->tailpred->next = n;
l->tailpred = n;
return n;
}
/**
* ibex_list_remove:
* @n: The node to remove.
*
* Remove a listnode from a list.
*
* Return value: Always the same as @n.
**/
struct _listnode *ibex_list_remove(struct _listnode *n)
{
n->next->prev = n->prev;
n->prev->next = n->next;
return n;
}
static struct _memblock *
memblock_addr(struct _block *block)
{
return (struct _memblock *)(((char *)block) - G_STRUCT_OFFSET(struct _memblock, data));
}
/**
* ibex_block_dirty:
* @block:
*
* Dirty a block. This will cause it to be written to disk on
* a cache sync, or when the block is flushed from the cache.
**/
void
ibex_block_dirty(struct _block *block)
{
memblock_addr(block)->flags |= BLOCK_DIRTY;
}
static void
sync_block(struct _memcache *block_cache, struct _memblock *memblock)
{
if (block_log)
printf("writing block %d\n", memblock->block);
lseek(block_cache->fd, memblock->block, SEEK_SET);
if (write(block_cache->fd, &memblock->data, sizeof(memblock->data)) != -1) {
memblock->flags &= ~BLOCK_DIRTY;
}
#ifdef IBEX_STATS
add_write(block_cache, memblock->block);
#endif
}
/**
* ibex_block_cache_sync:
* @block_cache:
*
* Ensure the block cache is fully synced to disk.
**/
void
ibex_block_cache_sync(struct _memcache *block_cache)
{
struct _memblock *memblock, *rootblock = 0;
memblock = (struct _memblock *)block_cache->nodes.head;
while (memblock->next) {
if (memblock->block == 0) {
rootblock = memblock;
} else {
if (memblock->flags & BLOCK_DIRTY) {
sync_block(block_cache, memblock);
}
}
memblock = memblock->next;
}
if (rootblock) {
struct _root *root = (struct _root *)&rootblock->data;
root->flags |= IBEX_ROOT_SYNCF;
sync_block(block_cache, rootblock);
}
if (fsync(block_cache->fd) == 0) {
block_cache->flags |= IBEX_ROOT_SYNCF;
}
#ifdef IBEX_STATS
dump_stats(block_cache);
#endif
}
/**
* ibex_block_cache_flush:
* @block_cache:
*
* Ensure the block cache is fully synced to disk, and then flush
* its contents from memory.
**/
void
ibex_block_cache_flush(struct _memcache *block_cache)
{
struct _memblock *mw, *mn;
ibex_block_cache_sync(block_cache);
mw = (struct _memblock *)block_cache->nodes.head;
mn = mw->next;
while (mn) {
g_hash_table_remove(block_cache->index, (void *)mw->block);
g_free(mw);
mw = mn;
mn = mn->next;
}
ibex_list_new(&block_cache->nodes);
}
/**
* ibex_block_read:
* @block_cache:
* @blockid:
*
* Read the data of a block by blockid. The data contents is backed by
* the block cache, and should be considered static.
*
* TODO; should this return a NULL block on error?
*
* Return value: The address of the block data (which may be cached).
**/
struct _block *
ibex_block_read(struct _memcache *block_cache, blockid_t blockid)
{
struct _memblock *memblock;
{
/* assert blockid<roof */
if (blockid > 0) {
struct _root *root = (struct _root *)ibex_block_read(block_cache, 0);
g_assert(blockid < root->roof);
}
}
memblock = g_hash_table_lookup(block_cache->index, (void *)blockid);
if (memblock) {
d(printf("foudn blockid in cache %d = %p\n", blockid, &memblock->data));
#if 0
if (blockid == 0) {
struct _root *root = &memblock->data;
d(printf("superblock state:\n"
" roof = %d\n free = %d\n words = %d\n names = %d\n tail = %d",
root->roof, root->free, root->words, root->names, root->tail));
}
#endif
/* 'access' page */
ibex_list_remove((struct _listnode *)memblock);
ibex_list_addtail(&block_cache->nodes, (struct _listnode *)memblock);
#ifdef IBEX_STATS
add_hit(block_cache, memblock->block);
#endif
return &memblock->data;
}
#ifdef IBEX_STATS
add_miss(block_cache, blockid);
add_read(block_cache, blockid);
#endif
if (block_log)
printf("miss block %d\n", blockid);
d(printf("loading blockid from disk %d\n", blockid));
memblock = g_malloc(sizeof(*memblock));
memblock->block = blockid;
memblock->flags = 0;
lseek(block_cache->fd, blockid, SEEK_SET);
memset(&memblock->data, 0, sizeof(memblock->data));
read(block_cache->fd, &memblock->data, sizeof(memblock->data));
ibex_list_addtail(&block_cache->nodes, (struct _listnode *)memblock);
g_hash_table_insert(block_cache->index, (void *)blockid, memblock);
if (block_cache->count >= CACHE_SIZE) {
struct _memblock *old = (struct _memblock *)block_cache->nodes.head;
d(printf("discaring cache block %d\n", old->block));
g_hash_table_remove(block_cache->index, (void *)old->block);
ibex_list_remove((struct _listnode *)old);
if (old->flags & BLOCK_DIRTY) {
/* are we about to un-sync the file? update root and sync it */
if (block_cache->flags & IBEX_ROOT_SYNCF) {
/* TODO: put the rootblock in the block_cache struct, not in the cache */
struct _memblock *rootblock = g_hash_table_lookup(block_cache->index, (void *)0);
struct _root *root = (struct _root *)&rootblock->data;
printf("Unsyncing root block\n");
g_assert(rootblock != NULL);
root->flags &= ~IBEX_ROOT_SYNCF;
sync_block(block_cache, rootblock);
if (fsync(block_cache->fd) == 0)
block_cache->flags &= ~IBEX_ROOT_SYNCF;
}
sync_block(block_cache, old);
}
g_free(old);
} else {
block_cache->count++;
}
d(printf(" --- cached blocks : %d\n", block_cache->count));
return &memblock->data;
}
/**
* ibex_block_cache_open:
* @name:
* @flags: Flags as to open(2), should use O_RDWR and optionally O_CREAT.
* @mode: Mose as to open(2)
*
* Open a block file.
*
* FIXME; this currently also initialises the word and name indexes
* because their pointers are stored in the root block. Should be
* upto the caller to manage these pointers/data.
*
* Return value: NULL if the backing file could not be opened.
**/
struct _memcache *
ibex_block_cache_open(const char *name, int flags, int mode)
{
struct _root *root;
struct _memcache *block_cache = g_malloc0(sizeof(*block_cache));
d(printf("opening ibex file: %s", name));
/* setup cache */
ibex_list_new(&block_cache->nodes);
block_cache->count = 0;
block_cache->index = g_hash_table_new(g_direct_hash, g_direct_equal);
block_cache->fd = open(name, flags, mode);
if (block_cache->fd == -1) {
g_hash_table_destroy(block_cache->index);
g_free(block_cache);
return NULL;
}
root = (struct _root *)ibex_block_read(block_cache, 0);
if (root->roof == 0
|| memcmp(root->version, "ibx3", 4)
|| ((root->flags & IBEX_ROOT_SYNCF) == 0)) {
(printf("Initialising superblock\n"));
/* reset root data */
memcpy(root->version, "ibx3", 4);
root->roof = 1024;
root->free = 0;
root->words = 0;
root->names = 0;
root->tail = 0; /* list of tail blocks */
root->flags = 0;
ibex_block_dirty((struct _block *)root);
/* reset the file contents */
ftruncate(block_cache->fd, 1024);
} else {
(printf("superblock already initialised:\n"
" roof = %d\n free = %d\n words = %d\n names = %d\n tail = %d",
root->roof, root->free, root->words, root->names, root->tail));
}
block_cache->flags = root->flags;
/* this should be moved higher up */
{
struct _IBEXWord *ibex_create_word_index(struct _memcache *bc, blockid_t *wordroot, blockid_t *nameroot);
block_cache->words = ibex_create_word_index(block_cache, &root->words, &root->names);
}
#ifdef IBEX_STATS
init_stats(block_cache);
#endif
return block_cache;
}
/**
* ibex_block_cache_close:
* @block_cache:
*
* Close the block file, sync any remaining cached data
* to disk, and free all resources.
**/
void
ibex_block_cache_close(struct _memcache *block_cache)
{
struct _memblock *mw, *mn;
ibex_block_cache_sync(block_cache);
close(block_cache->fd);
mw = (struct _memblock *)block_cache->nodes.head;
mn = mw->next;
while (mn) {
g_free(mw);
mw = mn;
mn = mw->next;
}
g_hash_table_destroy(block_cache->index);
g_free(block_cache);
}
/**
* ibex_block_free:
* @block_cache:
* @blockid:
*
* Return a block to the free pool.
**/
void
ibex_block_free(struct _memcache *block_cache, blockid_t blockid)
{
struct _root *root = (struct _root *)ibex_block_read(block_cache, 0);
struct _block *block = ibex_block_read(block_cache, blockid);
block->next = block_number(root->free);
root->free = blockid;
ibex_block_dirty((struct _block *)root);
ibex_block_dirty((struct _block *)block);
}
/**
* ibex_block_get:
* @block_cache:
*
* Allocate a new block, or access a previously freed block and return
* its block id. The block will have zeroed contents.
*
* Return value: 0 if there are no blocks left (disk full/read only
* file, etc).
**/
blockid_t
ibex_block_get(struct _memcache *block_cache)
{
struct _root *root = (struct _root *)ibex_block_read(block_cache, 0);
struct _block *block;
blockid_t head;
if (root->free) {
head = root->free;
block = ibex_block_read(block_cache, head);
root->free = block_location(block->next);
} else {
/* TODO: check the block will fit first */
/* TODO: no need to read this block, can allocate it manually (saves a syscall/read) */
head = root->roof;
root->roof += BLOCK_SIZE;
block = ibex_block_read(block_cache, head);
}
g_assert(head != 0);
d(printf("new block = %d\n", head));
block->next = 0;
block->used = 0;
ibex_block_dirty(block);
ibex_block_dirty((struct _block *)root);
return head;
}
