From: Marco van Wieringen Date: Thu, 3 Feb 2011 20:07:38 +0000 (+0100) Subject: Implement mntent_cache on top of the new htable code using a small htable big buffer... X-Git-Url: https://git.sur5r.net/?a=commitdiff_plain;h=69c4d8b41cf8b37b59060418191c7a340a333f44;p=bacula%2Fbacula Implement mntent_cache on top of the new htable code using a small htable big buffer of 128 Kb to start with. --- diff --git a/bacula/src/lib/mntent_cache.c b/bacula/src/lib/mntent_cache.c index 14b304da52..14422c0403 100644 --- a/bacula/src/lib/mntent_cache.c +++ b/bacula/src/lib/mntent_cache.c @@ -92,22 +92,12 @@ #include #endif -static char cache_initialized = 0; - -/** +/* * Protected data by mutex lock. */ static pthread_mutex_t mntent_cache_lock = PTHREAD_MUTEX_INITIALIZER; -static mntent_cache_entry_t *mntent_cache_entry_hashtable[NR_MNTENT_CACHE_ENTRIES]; static mntent_cache_entry_t *previous_cache_hit = NULL; - -/** - * Simple hash function. - */ -static uint32_t mntent_hash_function(uint32_t dev) -{ - return (dev % NR_MNTENT_CACHE_ENTRIES); -} +static htable *mntent_cache_entry_hashtable = NULL; /** * Add a new entry to the cache. @@ -116,38 +106,43 @@ static uint32_t mntent_hash_function(uint32_t dev) static void add_mntent_mapping(uint32_t dev, const char *special, const char *mountpoint, const char *fstype, const char *mntopts) { - uint32_t hash; + int len; mntent_cache_entry_t *mce; - /** - * Select the correct hash bucket. - */ - hash = mntent_hash_function(dev); - - /** - * See if this is the first being put into the hash bucket. + /* + * Calculate the length of all strings so we can allocate the buffer + * as one big chunk of memory using the hash_malloc method. */ - if (mntent_cache_entry_hashtable[hash] == (mntent_cache_entry_t *)NULL) { - mce = (mntent_cache_entry_t *)malloc(sizeof(mntent_cache_entry_t)); - memset((caddr_t)mce, 0, sizeof(mntent_cache_entry_t)); - mntent_cache_entry_hashtable[hash] = mce; - } else { - /** - * Walk the linked list in the hash bucket. - */ - for (mce = mntent_cache_entry_hashtable[hash]; mce->next != NULL; mce = mce->next) ; - mce->next = (mntent_cache_entry_t *)malloc(sizeof(mntent_cache_entry_t)); - mce = mce->next; - memset((caddr_t)mce, 0, sizeof(mntent_cache_entry_t)); + len = strlen(special) + 1; + len += strlen(mountpoint) + 1; + len += strlen(fstype) + 1; + if (mntopts) { + len += strlen(mntopts) + 1; } + /* + * We allocate all members of the hash entry in the same memory chunk. + */ + mce = (mntent_cache_entry_t *)mntent_cache_entry_hashtable->hash_malloc(sizeof(mntent_cache_entry_t) + len); mce->dev = dev; - mce->special = bstrdup(special); - mce->mountpoint = bstrdup(mountpoint); - mce->fstype = bstrdup(fstype); + + mce->special = (char *)mce + sizeof(mntent_cache_entry_t); + strcpy(mce->special, special); + + mce->mountpoint = mce->special + strlen(mce->special) + 1; + strcpy(mce->mountpoint, mountpoint); + + mce->fstype = mce->mountpoint + strlen(mce->mountpoint) + 1; + strcpy(mce->fstype, fstype); + if (mntopts) { - mce->mntopts = bstrdup(mntopts); + mce->mntopts = mce->fstype + strlen(mce->fstype) + 1; + strcpy(mce->mntopts, mntopts); + } else { + mce->mntopts = NULL; } + + mntent_cache_entry_hashtable->insert(mce->dev, mce); } /** @@ -317,15 +312,16 @@ static void refresh_mount_cache(void) */ static void clear_mount_cache() { - uint32_t hash; - mntent_cache_entry_t *mce, *mce_next; + mntent_cache_entry_t *mce = NULL; - if (cache_initialized == 0) { + if (!mntent_cache_entry_hashtable) { /** * Initialize the hash table. */ - memset((caddr_t)mntent_cache_entry_hashtable, 0, NR_MNTENT_CACHE_ENTRIES * sizeof(mntent_cache_entry_t *)); - cache_initialized = 1; + mntent_cache_entry_hashtable = (htable *)malloc(sizeof(htable)); + mntent_cache_entry_hashtable->init(mce, &mce->link, + NR_MNTENT_CACHE_ENTRIES, + NR_MNTENT_HTABLE_PAGES); } else { /** * Clear the previous_cache_hit. @@ -333,33 +329,12 @@ static void clear_mount_cache() previous_cache_hit = NULL; /** - * Walk all hash buckets. + * Destroy the current content and (re)initialize the hashtable. */ - for (hash = 0; hash < NR_MNTENT_CACHE_ENTRIES; hash++) { - /** - * Walk the content of this hash bucket. - */ - mce = mntent_cache_entry_hashtable[hash]; - mntent_cache_entry_hashtable[hash] = NULL; - while (mce != NULL) { - /** - * Save the pointer to the next entry. - */ - mce_next = mce->next; - - /** - * Free the structure. - */ - if (mce->mntopts) - free(mce->mntopts); - free(mce->fstype); - free(mce->mountpoint); - free(mce->special); - free(mce); - - mce = mce_next; - } - } + mntent_cache_entry_hashtable->destroy(); + mntent_cache_entry_hashtable->init(mce, &mce->link, + NR_MNTENT_CACHE_ENTRIES, + NR_MNTENT_HTABLE_PAGES); } } @@ -417,13 +392,12 @@ void flush_mntent_cache(void) */ mntent_cache_entry_t *find_mntent_mapping(uint32_t dev) { - uint32_t hash; - mntent_cache_entry_t *mce; + mntent_cache_entry_t *mce = NULL; /** * Initialize the cache if that was not done before. */ - if (cache_initialized == 0) { + if (!mntent_cache_entry_hashtable) { initialize_mntent_cache(); } @@ -439,25 +413,14 @@ mntent_cache_entry_t *find_mntent_mapping(uint32_t dev) */ P(mntent_cache_lock); - /** - * Select the correct hash bucket. - */ - hash = mntent_hash_function(dev); - - /** - * Walk the hash bucket. - */ - for (mce = mntent_cache_entry_hashtable[hash]; mce != NULL; mce = mce->next) { - if (mce->dev == dev) { - previous_cache_hit = mce; - V(mntent_cache_lock); - return mce; - } + mce = (mntent_cache_entry_t *)mntent_cache_entry_hashtable->lookup(dev); + if (mce) { + previous_cache_hit = mce; } /** * We are done walking the cache. */ V(mntent_cache_lock); - return NULL; + return mce; } diff --git a/bacula/src/lib/mntent_cache.h b/bacula/src/lib/mntent_cache.h index 39b7e2ff48..36bd5243e0 100644 --- a/bacula/src/lib/mntent_cache.h +++ b/bacula/src/lib/mntent_cache.h @@ -33,15 +33,24 @@ #ifndef _MNTENT_CACHE_H #define _MNTENT_CACHE_H 1 -#define NR_MNTENT_CACHE_ENTRIES 32 +/* + * Initial size of number of hash entries we expect in the cache. + * If more are needed the hash table will grow as needed. + */ +#define NR_MNTENT_CACHE_ENTRIES 256 + +/* + * Number of pages to allocate for the big_buffer used by htable. + */ +#define NR_MNTENT_HTABLE_PAGES 32 struct mntent_cache_entry_t { + hlink link; uint32_t dev; char *special; char *mountpoint; char *fstype; char *mntopts; - struct mntent_cache_entry_t *next; }; mntent_cache_entry_t *find_mntent_mapping(uint32_t dev);