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mdbx: add MDBX_READERS_LIMIT.

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Change-Id: I2ee97004c084aeb6290c56b8f6415adc464a1bcb
This commit is contained in:
Leonid Yuriev 2019-09-02 13:23:39 +03:00
parent 6f39d8228d
commit 098f8a0d77
2 changed files with 36 additions and 33 deletions
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4
src/elements/core.c
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@ -6323,7 +6323,7 @@ int __cold mdbx_env_set_maxdbs(MDBX_env *env, MDBX_dbi dbs) {
}
int __cold mdbx_env_set_maxreaders(MDBX_env *env, unsigned readers) {
if (unlikely(readers < 1 || readers > INT16_MAX))
if (unlikely(readers < 1 || readers > MDBX_READERS_LIMIT))
return MDBX_EINVAL;
if (unlikely(!env))
@ -6781,7 +6781,7 @@ static int __cold mdbx_setup_lck(MDBX_env *env, char *lck_pathname,
const size_t maxreaders =
((size_t)size - sizeof(MDBX_lockinfo)) / sizeof(MDBX_reader) + 1;
if (maxreaders < 2 || maxreaders > UINT16_MAX) {
if (maxreaders < 2 || maxreaders > MDBX_READERS_LIMIT) {
mdbx_error("lck-size too big (up to %" PRIuPTR " readers)", maxreaders);
err = MDBX_PROBLEM;
goto bailout;

65
src/elements/internals.h
View File

@ -336,37 +336,6 @@ typedef struct MDBX_page {
/* Size of the page header, excluding dynamic data at the end */
#define PAGEHDRSZ ((unsigned)offsetof(MDBX_page, mp_data))
/* The maximum size of a database page.
*
* It is 64K, but value-PAGEHDRSZ must fit in MDBX_page.mp_upper.
*
* MDBX will use database pages < OS pages if needed.
* That causes more I/O in write transactions: The OS must
* know (read) the whole page before writing a partial page.
*
* Note that we don't currently support Huge pages. On Linux,
* regular data files cannot use Huge pages, and in general
* Huge pages aren't actually pageable. We rely on the OS
* demand-pager to read our data and page it out when memory
* pressure from other processes is high. So until OSs have
* actual paging support for Huge pages, they're not viable. */
#define MAX_PAGESIZE 0x10000u
#define MIN_PAGESIZE 512u
#define MIN_MAPSIZE (MIN_PAGESIZE * MIN_PAGENO)
#if defined(_WIN32) || defined(_WIN64)
#define MAX_MAPSIZE32 UINT32_C(0x38000000)
#else
#define MAX_MAPSIZE32 UINT32_C(0x7ff80000)
#endif
#define MAX_MAPSIZE64 (MAX_PAGENO * (uint64_t)MAX_PAGESIZE)
#if MDBX_WORDBITS >= 64
#define MAX_MAPSIZE MAX_MAPSIZE64
#else
#define MAX_MAPSIZE MAX_MAPSIZE32
#endif /* MDBX_WORDBITS */
#pragma pack(pop)
/* Reader Lock Table
@ -527,6 +496,40 @@ typedef struct MDBX_lockinfo {
#define MDBX_ASSUME_MALLOC_OVERHEAD (sizeof(void *) * 2u)
#endif /* MDBX_ASSUME_MALLOC_OVERHEAD */
/* The maximum size of a database page.
*
* It is 64K, but value-PAGEHDRSZ must fit in MDBX_page.mp_upper.
*
* MDBX will use database pages < OS pages if needed.
* That causes more I/O in write transactions: The OS must
* know (read) the whole page before writing a partial page.
*
* Note that we don't currently support Huge pages. On Linux,
* regular data files cannot use Huge pages, and in general
* Huge pages aren't actually pageable. We rely on the OS
* demand-pager to read our data and page it out when memory
* pressure from other processes is high. So until OSs have
* actual paging support for Huge pages, they're not viable. */
#define MAX_PAGESIZE 0x10000u
#define MIN_PAGESIZE 512u
#define MIN_MAPSIZE (MIN_PAGESIZE * MIN_PAGENO)
#if defined(_WIN32) || defined(_WIN64)
#define MAX_MAPSIZE32 UINT32_C(0x38000000)
#else
#define MAX_MAPSIZE32 UINT32_C(0x7ff80000)
#endif
#define MAX_MAPSIZE64 (MAX_PAGENO * (uint64_t)MAX_PAGESIZE)
#if MDBX_WORDBITS >= 64
#define MAX_MAPSIZE MAX_MAPSIZE64
#define MDBX_READERS_LIMIT \
((65536 - sizeof(MDBX_lockinfo)) / sizeof(MDBX_reader) + 1)
#else
#define MDBX_READERS_LIMIT 1024
#define MAX_MAPSIZE MAX_MAPSIZE32
#endif /* MDBX_WORDBITS */
/*----------------------------------------------------------------------------*/
/* Two kind lists of pages (aka PNL) */