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Add the sqlite3_hard_heap_limit64() interface and the corresponding

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"PRAGMA hard_heap_limit=N" command.

FossilOrigin-Name: b0ccef61a7f92d20228becbf4f997bf0f4e46dad2deaf0896dc63b976ad1dd11
This commit is contained in:
drh
2019-04-25 18:15:38 +00:00
parent dbdd93b7e1
commit 10c0e7115b
11 changed files with 200 additions and 69 deletions
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54
src/sqlite.h.in
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@@ -6038,6 +6038,9 @@ int sqlite3_db_release_memory(sqlite3*);
/*
** CAPI3REF: Impose A Limit On Heap Size
**
** These interfaces impose limits on the amount of heap memory that will be
** by all database connections within a single process.
**
** ^The sqlite3_soft_heap_limit64() interface sets and/or queries the
** soft limit on the amount of heap memory that may be allocated by SQLite.
** ^SQLite strives to keep heap memory utilization below the soft heap
@@ -6048,20 +6051,41 @@ int sqlite3_db_release_memory(sqlite3*);
** an [SQLITE_NOMEM] error. In other words, the soft heap limit
** is advisory only.
**
** ^The return value from sqlite3_soft_heap_limit64() is the size of
** the soft heap limit prior to the call, or negative in the case of an
** ^The sqlite3_hard_heap_limit64(N) interface sets a hard upper bound of
** N bytes on the amount of memory that will be allocated. ^The
** sqlite3_hard_heap_limit64(N) interface is similar to
** sqlite3_soft_heap_limit64(N) except that memory allocations will fail
** when the hard heap limit is reached.
**
** ^The return value from both sqlite3_soft_heap_limit64() and
** sqlite3_hard_heap_limit64() is the size of
** the heap limit prior to the call, or negative in the case of an
** error. ^If the argument N is negative
** then no change is made to the soft heap limit. Hence, the current
** size of the soft heap limit can be determined by invoking
** sqlite3_soft_heap_limit64() with a negative argument.
** then no change is made to the heap limit. Hence, the current
** size of heap limits can be determined by invoking
** sqlite3_soft_heap_limit64(-1) or sqlite3_hard_heap_limit(-1).
**
** ^If the argument N is zero then the soft heap limit is disabled.
** ^Setting the heap limits to zero disables the heap limiter mechanism.
**
** ^(The soft heap limit is not enforced in the current implementation
** ^The soft heap limit may not be greater than the hard heap limit.
** ^If the hard heap limit is enabled and if sqlite3_soft_heap_limit(N)
** is invoked with a value of N that is greater than the hard heap limit,
** the the soft heap limit is set to the value of the hard heap limit.
** ^The soft heap limit is automatically enabled whenever the hard heap
** limit is enabled. ^When sqlite3_hard_heap_limit64(N) is invoked and
** the soft heap limit is outside the range of 1..N, then the soft heap
** limit is set to N. ^Invoking sqlite3_soft_heap_limit64(0) when the
** hard heap limit is enabled makes the soft heap limit equal to the
** hard heap limit.
**
** The soft heap limits can also be adjusted using
** [PRAGMA soft_heap_limit] and [PRAGMA hard_heap_limit].
**
** ^(The heap limits are not enforced in the current implementation
** if one or more of following conditions are true:
**
** <ul>
** <li> The soft heap limit is set to zero.
** <li> The limit value is set to zero.
** <li> Memory accounting is disabled using a combination of the
** [sqlite3_config]([SQLITE_CONFIG_MEMSTATUS],...) start-time option and
** the [SQLITE_DEFAULT_MEMSTATUS] compile-time option.
@@ -6072,21 +6096,11 @@ int sqlite3_db_release_memory(sqlite3*);
** from the heap.
** </ul>)^
**
** Beginning with SQLite [version 3.7.3] ([dateof:3.7.3]),
** the soft heap limit is enforced
** regardless of whether or not the [SQLITE_ENABLE_MEMORY_MANAGEMENT]
** compile-time option is invoked. With [SQLITE_ENABLE_MEMORY_MANAGEMENT],
** the soft heap limit is enforced on every memory allocation. Without
** [SQLITE_ENABLE_MEMORY_MANAGEMENT], the soft heap limit is only enforced
** when memory is allocated by the page cache. Testing suggests that because
** the page cache is the predominate memory user in SQLite, most
** applications will achieve adequate soft heap limit enforcement without
** the use of [SQLITE_ENABLE_MEMORY_MANAGEMENT].
**
** The circumstances under which SQLite will enforce the soft heap limit may
** The circumstances under which SQLite will enforce the heap limits may
** changes in future releases of SQLite.
*/
sqlite3_int64 sqlite3_soft_heap_limit64(sqlite3_int64 N);
sqlite3_int64 sqlite3_hard_heap_limit64(sqlite3_int64 N);
/*
** CAPI3REF: Deprecated Soft Heap Limit Interface