From: Timo Sirainen <timo.sirainen@open-xchange.com>
Date: Fri, 5 May 2023 14:10:55 +0000 (+0300)
Subject: lib: Add pool_add_external_ref() to allow pools to reference other pools
X-Git-Tag: 2.4.0~2086
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=5610cfde1fbc8d2046598e9e8a3042abddde1e06;p=thirdparty%2Fdovecot%2Fcore.git

lib: Add pool_add_external_ref() to allow pools to reference other pools

When the pool is destroyed, all its external references are unreferenced.
---

diff --git a/src/lib/lib.h b/src/lib/lib.h
index 7d945780c7..474fbf190b 100644
--- a/src/lib/lib.h
+++ b/src/lib/lib.h
@@ -37,6 +37,10 @@
 #include "macros.h"
 #include "failures.h"
 
+typedef struct buffer buffer_t;
+typedef struct buffer string_t;
+
+#include "array-decl.h" /* ARRAY*()s may exist in any header */
 #include "malloc-overflow.h"
 #include "data-stack.h"
 #include "mempool.h"
@@ -57,7 +61,6 @@ struct ostream;
 
 typedef void lib_atexit_callback_t(void);
 
-#include "array-decl.h" /* ARRAY*()s may exist in any header */
 #include "bits.h"
 #include "hash-decl.h" /* HASH_TABLE*()s may exist in any header */
 #include "strfuncs.h"
diff --git a/src/lib/mempool-alloconly.c b/src/lib/mempool-alloconly.c
index a9e8cd701a..798ea84f90 100644
--- a/src/lib/mempool-alloconly.c
+++ b/src/lib/mempool-alloconly.c
@@ -348,6 +348,7 @@ static void pool_alloconly_unref(pool_t *pool)
 	if (--apool->refcount > 0)
 		return;
 
+	pool_external_refs_unref(&apool->pool);
 	pool_alloconly_destroy(apool);
 }
 
diff --git a/src/lib/mempool.c b/src/lib/mempool.c
index a657481f93..68ec8f6684 100644
--- a/src/lib/mempool.c
+++ b/src/lib/mempool.c
@@ -1,6 +1,7 @@
 /* Copyright (c) 2005-2018 Dovecot authors, see the included COPYING file */
 
 #include "lib.h"
+#include "array.h"
 
 /* The various implementations of pools API assume that they'll never be
    asked for more than SSIZE_T_MAX bytes.  This is a sanity check to make
@@ -23,3 +24,21 @@ size_t pool_get_exp_grown_size(pool_t pool, size_t old_size, size_t min_size)
 	i_assert(exp_size >= min_size);
 	return exp_size;
 }
+
+void pool_add_external_ref(pool_t pool, pool_t ref_pool)
+{
+	if (!array_is_created(&pool->external_refs))
+		i_array_init(&pool->external_refs, 1);
+	array_push_back(&pool->external_refs, &ref_pool);
+	pool_ref(ref_pool);
+}
+
+void pool_external_refs_unref(pool_t pool)
+{
+	if (array_is_created(&pool->external_refs)) {
+		pool_t external_pool;
+		array_foreach_elem(&pool->external_refs, external_pool)
+			pool_unref(&external_pool);
+		array_free(&pool->external_refs);
+	}
+}
diff --git a/src/lib/mempool.h b/src/lib/mempool.h
index 9c7aca0581..918a6d4e6e 100644
--- a/src/lib/mempool.h
+++ b/src/lib/mempool.h
@@ -46,6 +46,7 @@ struct pool_vfuncs {
 
 struct pool {
 	const struct pool_vfuncs *v;
+	ARRAY(pool_t) external_refs;
 
 	bool alloconly_pool:1;
 	bool datastack_pool:1;
@@ -86,6 +87,10 @@ pool_t pool_allocfree_create_clean(const char *name);
    old_size + 1. */
 size_t pool_get_exp_grown_size(pool_t pool, size_t old_size, size_t min_size);
 
+/* Reference another memory pool in the given pool. When the pool is freed,
+   the referenced memory pools are also unreferenced. */
+void pool_add_external_ref(pool_t pool, pool_t ref_pool);
+
 /* We require sizeof(type) to be <= UINT_MAX. This allows compiler to optimize
    away the entire MALLOC_MULTIPLY() call on 64bit systems. */
 #define p_new(pool, type, count) \
@@ -175,5 +180,6 @@ size_t pool_allocfree_get_total_alloc_size(pool_t pool);
 
 /* private: */
 void pool_system_free(pool_t pool, void *mem);
+void pool_external_refs_unref(pool_t pool);
 
 #endif