From a4bbe57f8ba4c7d88ba6d16a63171c2ec2ce02ad Mon Sep 17 00:00:00 2001 From: Howard Chu Date: Thu, 18 Jul 2013 10:40:21 -0700 Subject: [PATCH] Add mdb_reader_check() --- libraries/liblmdb/lmdb.h | 8 ++ libraries/liblmdb/mdb.c | 152 ++++++++++++++++++++++++++++++++++- libraries/liblmdb/mdb_stat.1 | 5 +- libraries/liblmdb/mdb_stat.c | 8 +- 4 files changed, 170 insertions(+), 3 deletions(-) diff --git a/libraries/liblmdb/lmdb.h b/libraries/liblmdb/lmdb.h index af046d19c8..b3cd5ef79e 100644 --- a/libraries/liblmdb/lmdb.h +++ b/libraries/liblmdb/lmdb.h @@ -1315,6 +1315,14 @@ typedef int (MDB_msg_func)(const char *msg, void *ctx); * @return < 0 on failure, 0 on success. */ int mdb_reader_list(MDB_env *env, MDB_msg_func *func, void *ctx); + + /** @brief Check for stale entries in the reader lock table. + * + * @param[in] env An environment handle returned by #mdb_env_create() + * @param[out] dead Number of stale slots that were cleared + * @return 0 on success, non-zero on failure. + */ +int mdb_reader_check(MDB_env *env, int *dead); /** @} */ #ifdef __cplusplus diff --git a/libraries/liblmdb/mdb.c b/libraries/liblmdb/mdb.c index 5d08b42d9c..b36ff2bb4f 100644 --- a/libraries/liblmdb/mdb.c +++ b/libraries/liblmdb/mdb.c @@ -952,6 +952,8 @@ struct MDB_env { #define MDB_ENV_ACTIVE 0x20000000U /** me_txkey is set */ #define MDB_ENV_TXKEY 0x10000000U + /** Have liveness lock in reader table */ +#define MDB_LIVE_READER 0x08000000U uint32_t me_flags; /**< @ref mdb_env */ unsigned int me_psize; /**< size of a page, from #GET_PAGESIZE */ unsigned int me_maxreaders; /**< size of the reader table */ @@ -983,6 +985,7 @@ struct MDB_env { /** Max size of a node on a page */ unsigned int me_nodemax; #ifdef _WIN32 + int me_pidquery; /**< Used in OpenProcess */ HANDLE me_rmutex; /* Windows mutexes don't reside in shared mem */ HANDLE me_wmutex; #elif defined(MDB_USE_POSIX_SEM) @@ -1994,6 +1997,56 @@ mdb_cursors_close(MDB_txn *txn, unsigned merge) static void mdb_txn_reset0(MDB_txn *txn, const char *act); +#ifdef _WIN32 +enum Pidlock_op { + Pidset, Pidcheck +}; +#else +enum Pidlock_op { + Pidset = F_SETLK, Pidcheck = F_GETLK +}; +#endif + +/** Set or check a pid lock. Set returns 0 on success. + * Check returns 0 if lock exists (meaning the process is alive). + * + * On Windows Pidset is a no-op, we merely check for the existence + * of the process with the given pid. On POSIX we use a single byte + * lock on the lockfile, set at an offset equal to the pid. + */ +static int +mdb_reader_pid(MDB_env *env, enum Pidlock_op op, pid_t pid) +{ +#ifdef _WIN32 + HANDLE h; + int ver, query; + switch(op) { + case Pidset: + break; + case Pidcheck: + h = OpenProcess(env->me_pidquery, FALSE, pid); + if (!h) + return GetLastError(); + CloseHandle(h); + break; + } + return 0; +#else + int rc; + struct flock lock_info; + memset((void *)&lock_info, 0, sizeof(lock_info)); + lock_info.l_type = F_WRLCK; + lock_info.l_whence = SEEK_SET; + lock_info.l_start = pid; + lock_info.l_len = 1; + while ((rc = fcntl(env->me_lfd, op, &lock_info)) && + (rc = ErrCode()) == EINTR) ; + if (op == F_GETLK && rc == 0 && lock_info.l_type == F_UNLCK) + rc = -1; + return rc; +#endif +} + /** Common code for #mdb_txn_begin() and #mdb_txn_renew(). * @param[in] txn the transaction handle to initialize * @return 0 on success, non-zero on failure. @@ -2033,6 +2086,14 @@ mdb_txn_renew0(MDB_txn *txn) UNLOCK_MUTEX_R(env); return MDB_READERS_FULL; } + if (!(env->me_flags & MDB_LIVE_READER)) { + rc = mdb_reader_pid(env, Pidset, pid); + if (rc) { + UNLOCK_MUTEX_R(env); + return rc; + } + env->me_flags |= MDB_LIVE_READER; + } env->me_txns->mti_readers[i].mr_pid = pid; env->me_txns->mti_readers[i].mr_tid = tid; if (i >= env->me_txns->mti_numreaders) @@ -3161,6 +3222,14 @@ mdb_env_open2(MDB_env *env) LONG sizelo, sizehi; sizelo = env->me_mapsize & 0xffffffff; sizehi = env->me_mapsize >> 16 >> 16; /* only needed on Win64 */ + + /* See if we should use QueryLimited */ + rc = GetVersion(); + if ((rc & 0xff) > 5) + env->me_pidquery = PROCESS_QUERY_LIMITED_INFORMATION; + else + env->me_pidquery = PROCESS_QUERY_INFORMATION; + /* Windows won't create mappings for zero length files. * Just allocate the maxsize right now. */ @@ -7930,7 +7999,7 @@ int mdb_reader_list(MDB_env *env, MDB_msg_func *func, void *ctx) if (!env->me_txns) { return func("(no reader locks)\n", ctx); } - rdrs = env->me_numreaders; + rdrs = env->me_maxreaders; mr = env->me_txns->mti_readers; for (i=0; i> 1; + cursor = base + pivot + 1; + val = pid - ids[cursor]; + + if( val < 0 ) { + n = pivot; + + } else if ( val > 0 ) { + base = cursor; + n -= pivot + 1; + + } else { + /* found, so it's a duplicate */ + return -1; + } + } + + if( val > 0 ) { + ++cursor; + } + ids[0]++; + for (n = ids[0]; n > cursor; n--) + ids[n] = ids[n-1]; + ids[n] = pid; + return 0; +} + +int mdb_reader_check(MDB_env *env, int *dead) +{ + unsigned int i, j, rdrs; + MDB_reader *mr; + pid_t *pids, pid; + int count = 0; + + if (!env) + return EINVAL; + if (dead) + *dead = 0; + if (!env->me_txns) + return MDB_SUCCESS; + rdrs = env->me_maxreaders; + pids = malloc((rdrs+1) * sizeof(pid_t)); + if (!pids) + return ENOMEM; + pids[0] = 0; + mr = env->me_txns->mti_readers; + j = 0; + for (i=0; ime_pid) { + pid = mr[i].mr_pid; + if (mdb_pid_insert(pids, pid) == 0) { + if (mdb_reader_pid(env, Pidcheck, pid)) { + LOCK_MUTEX_R(env); + for (j=i; j 1) { + int dead; + mdb_reader_check(env, &dead); + printf(" %d stale readers cleared.\n", dead); + rc = mdb_reader_list(env, (MDB_msg_func *)fputs, stdout); + } if (!(subname || alldbs || freinfo)) goto env_close; } -- 2.39.5