** Merged from IBEX_DISK branch to head.

2000-09-19  Not Zed  <NotZed@HelixCode.com>

	** Merged from IBEX_DISK branch to head.

svn path=/trunk/; revision=5500

1 files changed, 481 insertions, 0 deletions

diff --git a/libibex/block.c b/libibex/block.c
new file mode 100644
index 0000000000..53579523bd
--- /dev/null
+++ b/libibex/block.c
@@ -0,0 +1,481 @@
+/* -*- 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*/
+
+
+#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)
+{
+	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;
+
+	memblock = (struct _memblock *)block_cache->nodes.head;
+	while (memblock->next) {
+		if (memblock->flags & BLOCK_DIRTY) {
+			sync_block(block_cache, memblock);
+		}
+		memblock = memblock->next;
+	}
+	fsync(block_cache->fd);
+
+#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));
+		/* '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
+	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) {
+			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)) {
+		d(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 */
+		ibex_block_dirty((struct _block *)root);
+	} else {
+		d(printf("superblock already initialised:\n"
+			 " roof = %d\n free = %d\n words = %d\n names = %d\n",
+			 root->roof, root->free, root->words, root->names));
+	}
+	/* 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 = 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;
+}