Mercurial > dovecot > core-2.2
view src/lib-sql/sql-db-cache.c @ 22715:20415dd0b85a
dsync: Add per-mailbox sync lock that is always used.
Both importing and exporting gets the lock before they even sync the
mailbox. The lock is kept until the import/export finishes. This guarantees
that no matter how dsync is run, two dsyncs can't be working on the same
mailbox at the same time.
This lock is in addition to the optional per-user lock enabled by the -l
parameter. If the -l parameter is used, the same lock timeout is used for
the per-mailbox lock. Otherwise 30s timeout is used.
This should help to avoid email duplication when replication is enabled for
public namespaces, and maybe in some other rare situations as well.
author | Timo Sirainen <timo.sirainen@dovecot.fi> |
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date | Thu, 28 Dec 2017 14:10:23 +0200 |
parents | cb108f786fb4 |
children |
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/* Copyright (c) 2004-2018 Dovecot authors, see the included COPYING file */ #include "lib.h" #include "array.h" #include "hash.h" #include "sql-api-private.h" #include "sql-db-cache.h" #define SQL_DB_CACHE_CONTEXT(obj) \ MODULE_CONTEXT(obj, sql_db_cache_module) struct sql_db_cache_context { union sql_db_module_context module_ctx; struct sql_db *prev, *next; /* These are set while refcount=0 */ struct sql_db_cache *cache; int refcount; char *key; void (*orig_deinit)(struct sql_db *db); }; struct sql_db_cache { HASH_TABLE(char *, struct sql_db *) dbs; unsigned int unused_count, max_unused_connections; struct sql_db *unused_tail, *unused_head; }; static MODULE_CONTEXT_DEFINE_INIT(sql_db_cache_module, &sql_db_module_register); static void sql_db_cache_db_deinit(struct sql_db *db) { struct sql_db_cache_context *ctx = SQL_DB_CACHE_CONTEXT(db); struct sql_db_cache_context *head_ctx; if (--ctx->refcount > 0) return; ctx->cache->unused_count++; if (ctx->cache->unused_tail == NULL) ctx->cache->unused_tail = db; else { head_ctx = SQL_DB_CACHE_CONTEXT(ctx->cache->unused_head); head_ctx->next = db; } ctx->prev = ctx->cache->unused_head; ctx->cache->unused_head = db; } static void sql_db_cache_unlink(struct sql_db_cache_context *ctx) { struct sql_db_cache_context *prev_ctx, *next_ctx; i_assert(ctx->refcount == 0); if (ctx->prev == NULL) ctx->cache->unused_tail = ctx->next; else { prev_ctx = SQL_DB_CACHE_CONTEXT(ctx->prev); prev_ctx->next = ctx->next; } if (ctx->next == NULL) ctx->cache->unused_head = ctx->prev; else { next_ctx = SQL_DB_CACHE_CONTEXT(ctx->next); next_ctx->prev = ctx->prev; } ctx->cache->unused_count--; } static void sql_db_cache_free_tail(struct sql_db_cache *cache) { struct sql_db *db; struct sql_db_cache_context *ctx; db = cache->unused_tail; ctx = SQL_DB_CACHE_CONTEXT(db); sql_db_cache_unlink(ctx); hash_table_remove(cache->dbs, ctx->key); i_free(ctx->key); ctx->orig_deinit(db); i_free(ctx); } static void sql_db_cache_drop_oldest(struct sql_db_cache *cache) { while (cache->unused_count >= cache->max_unused_connections) sql_db_cache_free_tail(cache); } struct sql_db * sql_db_cache_new(struct sql_db_cache *cache, const char *db_driver, const char *connect_string) { struct sql_db_cache_context *ctx; struct sql_db *db; char *key; key = i_strdup_printf("%s\t%s", db_driver, connect_string); db = hash_table_lookup(cache->dbs, key); if (db != NULL) { ctx = SQL_DB_CACHE_CONTEXT(db); if (ctx->refcount == 0) { sql_db_cache_unlink(ctx); ctx->prev = ctx->next = NULL; } i_free(key); } else { sql_db_cache_drop_oldest(cache); ctx = i_new(struct sql_db_cache_context, 1); ctx->cache = cache; ctx->key = key; db = sql_init(db_driver, connect_string); ctx->orig_deinit = db->v.deinit; db->v.deinit = sql_db_cache_db_deinit; MODULE_CONTEXT_SET(db, sql_db_cache_module, ctx); hash_table_insert(cache->dbs, ctx->key, db); } ctx->refcount++; return db; } struct sql_db_cache *sql_db_cache_init(unsigned int max_unused_connections) { struct sql_db_cache *cache; cache = i_new(struct sql_db_cache, 1); hash_table_create(&cache->dbs, default_pool, 0, str_hash, strcmp); cache->max_unused_connections = max_unused_connections; return cache; } void sql_db_cache_deinit(struct sql_db_cache **_cache) { struct sql_db_cache *cache = *_cache; *_cache = NULL; while (cache->unused_tail != NULL) sql_db_cache_free_tail(cache); hash_table_destroy(&cache->dbs); i_free(cache); }