Some changes and bug fixes to make the API better to use:
- added user data pointer to cache_transaction notifier - added functions block_cache_set_dirty(), and block_cache_make_writable() - cache_transaction_next_block() let's you iterate over all blocks in the transaction - instead of binding the block contents to the transaction (read-only checked out blocks did only see the unchanged blocks until the transaction was closed) the block now always shows the current data - even if the old way had some advantages, it was terrible to use - the blocks were not correctly added to the transaction - improved debug output - can check if the read-only blocks were changed accidently (compile time option) git-svn-id: file:///srv/svn/repos/haiku/trunk/current@9936 a95241bf-73f2-0310-859d-f6bbb57e9c96
This commit is contained in:
Axel Dörfler
parent
9de65b05cc
commit
6d6292cffa
172
src/kernel/core/cache/block_cache.cpp
vendored
172
src/kernel/core/cache/block_cache.cpp
vendored
@ -16,6 +16,7 @@
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#include <unistd.h>
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#include <stdlib.h>
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#include <string.h>
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#include <errno.h>
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// ToDo: this is a naive implementation to test the API:
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@ -27,6 +28,14 @@
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// 4) dirty blocks are only written back if asked for
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// 5) blocks are never removed yet
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#define TRACE_BLOCK_CACHE
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#ifdef TRACE_BLOCK_CACHE
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# define TRACE(x) dprintf x
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#else
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# define TRACE(x) ;
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#endif
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#define DEBUG_CHANGED
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struct cache_transaction;
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typedef DoublyLinked::Link block_link;
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@ -37,9 +46,13 @@ struct cached_block {
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block_link previous_transaction_link;
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off_t block_number;
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void *data;
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void *updated;
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void *original;
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#ifdef DEBUG_CHANGED
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void *compare;
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#endif
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int32 ref_count;
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int32 lock;
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bool is_dirty;
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cache_transaction *transaction;
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cache_transaction *previous_transaction;
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};
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@ -57,11 +70,13 @@ struct block_cache {
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typedef DoublyLinked::List<cached_block, &cached_block::previous_transaction_link> block_list;
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struct cache_transaction {
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cache_transaction *next;
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int32 id;
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int32 num_blocks;
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cached_block *first_block;
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block_list blocks;
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transaction_notification_hook notification_hook;
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void *notification_data;
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bool open;
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};
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@ -183,8 +198,7 @@ static void
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free_cached_block(cached_block *block)
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{
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free(block->data);
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if (block->data != block->updated)
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free(block->updated);
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free(block->original);
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free(block);
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}
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@ -209,7 +223,10 @@ new_cached_block(block_cache *cache, off_t blockNumber, bool cleared = false)
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block->lock = 0;
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block->transaction_next = NULL;
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block->transaction = block->previous_transaction = NULL;
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block->updated = NULL;
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block->original = NULL;
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#ifdef DEBUG_CHANGED
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block->compare = NULL;
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#endif
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hash_insert(cache->hash, block);
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@ -220,6 +237,11 @@ new_cached_block(block_cache *cache, off_t blockNumber, bool cleared = false)
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static void
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put_cached_block(block_cache *cache, cached_block *block)
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{
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#ifdef DEBUG_CHANGED
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if (!block->is_dirty && block->compare != NULL && memcmp(block->data, block->compare, cache->block_size))
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panic("block_cache: supposed to be clean block was changed!\n");
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#endif
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block->lock--;
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}
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@ -293,7 +315,7 @@ get_writable_cached_block(block_cache *cache, off_t blockNumber, off_t base, off
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if (cleared)
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memset(block->data, 0, cache->block_size);
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block->updated = block->data;
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block->is_dirty = true;
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// mark the block as dirty
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return block->data;
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@ -312,7 +334,7 @@ get_writable_cached_block(block_cache *cache, off_t blockNumber, off_t base, off
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// get new transaction
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cache_transaction *transaction = lookup_transaction(cache, transactionID);
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if (transaction == NULL) {
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panic("block_cache_get_writable(): invalid transaction!\n");
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panic("block_cache_get_writable(): invalid transaction %ld!\n", transactionID);
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return NULL;
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}
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if (!transaction->open) {
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@ -324,25 +346,33 @@ get_writable_cached_block(block_cache *cache, off_t blockNumber, off_t base, off
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// attach the block to the transaction block list
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block->transaction_next = transaction->first_block;
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transaction->first_block = block->transaction_next;
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transaction->first_block = block;
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transaction->num_blocks++;
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}
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if (block->updated == NULL) {
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block->updated = malloc(cache->block_size);
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if (block->updated == NULL) {
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if (block->data != NULL && block->original == NULL) {
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// we already have data, so we need to save it
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block->original = malloc(cache->block_size);
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if (block->original == NULL) {
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put_cached_block(cache, block);
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return NULL;
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}
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if (!cleared)
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memcpy(block->updated, block->data, cache->block_size);
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memcpy(block->original, block->data, cache->block_size);
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}
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if (cleared)
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memset(block->updated, 0, cache->block_size);
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return block->updated;
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if (block->data == NULL && cleared) {
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// there is no data yet, we need a clean new block
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block->data = malloc(cache->block_size);
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if (block->data == NULL) {
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put_cached_block(cache, block);
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return NULL;
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}
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memset(block->data, 0, cache->block_size);
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}
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block->is_dirty = true;
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return block->data;
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}
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@ -352,18 +382,24 @@ write_cached_block(block_cache *cache, cached_block *block, bool deleteTransacti
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cache_transaction *previous = block->previous_transaction;
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int32 blockSize = cache->block_size;
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if (write_pos(cache->fd, block->block_number * blockSize, block->data, blockSize) < blockSize) {
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dprintf("could not write back block %Ld\n", block->block_number);
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TRACE(("write_cached_block(block %Ld)\n", block->block_number));
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ssize_t written = write_pos(cache->fd, block->block_number * blockSize, block->data, blockSize);
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if (written < blockSize) {
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dprintf("could not write back block %Ld (errno = %d (%s))\n", block->block_number, errno, strerror(errno));
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return B_IO_ERROR;
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}
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block->is_dirty = false;
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if (previous != NULL) {
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previous->blocks.Remove(block);
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block->previous_transaction = NULL;
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if (--previous->num_blocks == 0) {
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if (previous->notification_hook != NULL)
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previous->notification_hook(previous->id);
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previous->notification_hook(previous->id, previous->notification_data);
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if (deleteTransaction)
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delete_transaction(cache, previous);
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@ -379,7 +415,7 @@ write_cached_block(block_cache *cache, cached_block *block, bool deleteTransacti
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extern "C" int32
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cache_transaction_start(void *_cache, transaction_notification_hook hook)
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cache_transaction_start(void *_cache, transaction_notification_hook hook, void *data)
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{
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block_cache *cache = (block_cache *)_cache;
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@ -391,8 +427,11 @@ cache_transaction_start(void *_cache, transaction_notification_hook hook)
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transaction->num_blocks = 0;
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transaction->first_block = NULL;
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transaction->notification_hook = hook;
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transaction->notification_data = data;
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transaction->open = true;
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TRACE(("cache_transaction_start(): id %ld started\n", transaction->id));
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BenaphoreLocker locker(cache);
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hash_insert(cache->transaction_hash, transaction);
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@ -436,13 +475,15 @@ cache_transaction_end(void *_cache, int32 id)
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block_cache *cache = (block_cache *)_cache;
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BenaphoreLocker locker(cache);
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TRACE(("cache_transaction_end(id = %ld)\n", id));
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cache_transaction *transaction = lookup_transaction(cache, id);
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if (transaction == NULL) {
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panic("cache_transaction_end(): invalid transaction ID\n");
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return B_BAD_VALUE;
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}
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// iterate through all blocks and make the updated contents current
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// iterate through all blocks and free the unchanged original contents
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cached_block *block = transaction->first_block, *next;
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for (; block != NULL; block = next) {
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@ -452,17 +493,11 @@ cache_transaction_end(void *_cache, int32 id)
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// need to write back pending changes
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write_cached_block(cache, block);
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}
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// ToDo: unfortunately, at least for now, we have to keep the
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// block data pointer constant. Therefore, we have to copy
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// the data.
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if (block->data != NULL) {
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memcpy(block->data, block->updated, cache->block_size);
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free(block->updated);
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} else
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block->data = block->updated;
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block->updated = NULL;
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if (block->original != NULL) {
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free(block->original);
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block->original = NULL;
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}
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// move the block to the previous transaction list
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transaction->blocks.Add(block);
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@ -488,6 +523,39 @@ cache_transaction_abort(void *_cache, int32 id)
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}
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extern "C" status_t
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cache_transaction_next_block(void *_cache, int32 id, uint32 *_cookie, off_t *_blockNumber,
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void **_data, void **_unchangedData)
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{
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cached_block *block = (cached_block *)*_cookie;
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block_cache *cache = (block_cache *)_cache;
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BenaphoreLocker locker(cache);
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cache_transaction *transaction = lookup_transaction(cache, id);
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if (transaction == NULL)
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return B_BAD_VALUE;
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if (block == NULL)
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block = transaction->first_block;
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else
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block = block->transaction_next;
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if (block == NULL)
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return B_ENTRY_NOT_FOUND;
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if (_blockNumber)
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*_blockNumber = block->block_number;
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if (_data)
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*_data = block->data;
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if (_unchangedData)
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*_unchangedData = block->original;
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*_cookie = (uint32)block;
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return B_OK;
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}
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// #pragma mark -
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// public interface
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@ -545,6 +613,7 @@ block_cache_create(int fd, off_t numBlocks, size_t blockSize)
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cache->fd = fd;
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cache->max_blocks = numBlocks;
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cache->block_size = blockSize;
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cache->next_transaction_id = 1;
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return cache;
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@ -573,7 +642,7 @@ block_cache_sync(void *_cache)
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cached_block *block;
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while ((block = (cached_block *)hash_next(cache->hash, &iterator)) != NULL) {
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if (block->previous_transaction != NULL
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|| (block->transaction == NULL && block->updated)) {
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|| (block->transaction == NULL && block->is_dirty)) {
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status_t status = write_cached_block(cache, block);
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if (status != B_OK)
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return status;
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@ -585,10 +654,26 @@ block_cache_sync(void *_cache)
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}
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extern "C" status_t
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block_cache_make_writable(void *_cache, off_t blockNumber, int32 transaction)
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{
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// ToDo: this can be done better!
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void *block = block_cache_get_writable_etc(_cache, blockNumber, blockNumber, 1, transaction);
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if (block != NULL) {
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put_cached_block((block_cache *)_cache, blockNumber);
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return B_OK;
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}
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return B_ERROR;
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}
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extern "C" void *
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block_cache_get_writable_etc(void *_cache, off_t blockNumber, off_t base, off_t length,
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int32 transaction)
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{
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TRACE(("block_cache_get_writable_etc(block = %Ld, transaction = %ld)\n", blockNumber, transaction));
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return get_writable_cached_block((block_cache *)_cache, blockNumber,
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base, length, transaction, false);
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}
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@ -604,6 +689,8 @@ block_cache_get_writable(void *_cache, off_t blockNumber, int32 transaction)
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extern "C" void *
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block_cache_get_empty(void *_cache, off_t blockNumber, int32 transaction)
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{
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TRACE(("block_cache_get_empty(block = %Ld, transaction = %ld)\n", blockNumber, transaction));
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return get_writable_cached_block((block_cache *)_cache, blockNumber,
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blockNumber, 1, transaction, true);
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}
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@ -619,6 +706,13 @@ block_cache_get_etc(void *_cache, off_t blockNumber, off_t base, off_t length)
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if (block == NULL)
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return NULL;
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#ifdef DEBUG_CHANGED
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if (block->compare == NULL) {
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block->compare = malloc(cache->block_size);
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if (block->compare != NULL)
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memcpy(block->compare, block->data, cache->block_size);
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}
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#endif
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return block->data;
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}
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@ -630,6 +724,18 @@ block_cache_get(void *_cache, off_t blockNumber)
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}
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extern "C" status_t
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block_cache_set_dirty(void *_cache, off_t blockNumber, bool isDirty, int32 transaction)
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{
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// not yet implemented
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// Note, you must only use this function on blocks that were acquired writable!
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if (isDirty)
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panic("block_cache_set_dirty(): not yet implemented that way!\n");
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return B_OK;
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}
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extern "C" void
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block_cache_put(void *_cache, off_t blockNumber)
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{
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@ -643,6 +749,7 @@ block_cache_put(void *_cache, off_t blockNumber)
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// #pragma mark -
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// private BeOS compatible interface (to be removed)
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#if 0
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void
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put_cache_entry(int fd, cached_block *entry)
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@ -865,3 +972,4 @@ set_blocks_info(int fd, off_t *blocks, int numBlocks,
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return -1;
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}
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#endif
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