From 2458e5481434bb9c7b99813a449f6cbdf521c028 Mon Sep 17 00:00:00 2001
From: Oran Agra <oran@redislabs.com>
Date: Sun, 20 Sep 2020 13:43:28 +0300
Subject: [PATCH] RM_GetContextFlags provides indication that we're in a fork
child (#7783)
---
src/aof.c | 4 ++--
src/childinfo.c | 6 +++---
src/module.c | 5 +++--
src/rdb.c | 8 ++++----
src/redismodule.h | 2 ++
src/scripting.c | 2 +-
src/server.c | 8 ++++++--
src/server.h | 11 +++++++----
8 files changed, 28 insertions(+), 18 deletions(-)
diff --git a/src/aof.c b/src/aof.c
index e01a11342..c444c299c 100644
--- a/src/aof.c
+++ b/src/aof.c
@@ -1603,7 +1603,7 @@ int rewriteAppendOnlyFileBackground(void) {
if (hasActiveChildProcess()) return C_ERR;
if (aofCreatePipes() != C_OK) return C_ERR;
openChildInfoPipe();
- if ((childpid = redisFork()) == 0) {
+ if ((childpid = redisFork(CHILD_TYPE_AOF)) == 0) {
char tmpfile[256];
/* Child */
@@ -1611,7 +1611,7 @@ int rewriteAppendOnlyFileBackground(void) {
redisSetCpuAffinity(server.aof_rewrite_cpulist);
snprintf(tmpfile,256,"temp-rewriteaof-bg-%d.aof", (int) getpid());
if (rewriteAppendOnlyFile(tmpfile) == C_OK) {
- sendChildCOWInfo(CHILD_INFO_TYPE_AOF, "AOF rewrite");
+ sendChildCOWInfo(CHILD_TYPE_AOF, "AOF rewrite");
exitFromChild(0);
} else {
exitFromChild(1);
diff --git a/src/childinfo.c b/src/childinfo.c
index fa0600552..f95ae9647 100644
--- a/src/childinfo.c
+++ b/src/childinfo.c
@@ -76,11 +76,11 @@ void receiveChildInfo(void) {
if (read(server.child_info_pipe[0],&server.child_info_data,wlen) == wlen &&
server.child_info_data.magic == CHILD_INFO_MAGIC)
{
- if (server.child_info_data.process_type == CHILD_INFO_TYPE_RDB) {
+ if (server.child_info_data.process_type == CHILD_TYPE_RDB) {
server.stat_rdb_cow_bytes = server.child_info_data.cow_size;
- } else if (server.child_info_data.process_type == CHILD_INFO_TYPE_AOF) {
+ } else if (server.child_info_data.process_type == CHILD_TYPE_AOF) {
server.stat_aof_cow_bytes = server.child_info_data.cow_size;
- } else if (server.child_info_data.process_type == CHILD_INFO_TYPE_MODULE) {
+ } else if (server.child_info_data.process_type == CHILD_TYPE_MODULE) {
server.stat_module_cow_bytes = server.child_info_data.cow_size;
}
}
diff --git a/src/module.c b/src/module.c
index c6ea0cbbb..17b72d059 100644
--- a/src/module.c
+++ b/src/module.c
@@ -1991,6 +1991,7 @@ int RM_GetContextFlags(RedisModuleCtx *ctx) {
/* Presence of children processes. */
if (hasActiveChildProcess()) flags |= REDISMODULE_CTX_FLAGS_ACTIVE_CHILD;
+ if (server.in_fork_child) flags |= REDISMODULE_CTX_FLAGS_IS_CHILD;
return flags;
}
@@ -6899,7 +6900,7 @@ int RM_Fork(RedisModuleForkDoneHandler cb, void *user_data) {
}
openChildInfoPipe();
- if ((childpid = redisFork()) == 0) {
+ if ((childpid = redisFork(CHILD_TYPE_MODULE)) == 0) {
/* Child */
redisSetProcTitle("redis-module-fork");
} else if (childpid == -1) {
@@ -6919,7 +6920,7 @@ int RM_Fork(RedisModuleForkDoneHandler cb, void *user_data) {
* retcode will be provided to the done handler executed on the parent process.
*/
int RM_ExitFromChild(int retcode) {
- sendChildCOWInfo(CHILD_INFO_TYPE_MODULE, "Module fork");
+ sendChildCOWInfo(CHILD_TYPE_MODULE, "Module fork");
exitFromChild(retcode);
return REDISMODULE_OK;
}
diff --git a/src/rdb.c b/src/rdb.c
index d0a3c3210..d2c085d4d 100644
--- a/src/rdb.c
+++ b/src/rdb.c
@@ -1385,7 +1385,7 @@ int rdbSaveBackground(char *filename, rdbSaveInfo *rsi) {
server.lastbgsave_try = time(NULL);
openChildInfoPipe();
- if ((childpid = redisFork()) == 0) {
+ if ((childpid = redisFork(CHILD_TYPE_RDB)) == 0) {
int retval;
/* Child */
@@ -1393,7 +1393,7 @@ int rdbSaveBackground(char *filename, rdbSaveInfo *rsi) {
redisSetCpuAffinity(server.bgsave_cpulist);
retval = rdbSave(filename,rsi);
if (retval == C_OK) {
- sendChildCOWInfo(CHILD_INFO_TYPE_RDB, "RDB");
+ sendChildCOWInfo(CHILD_TYPE_RDB, "RDB");
}
exitFromChild((retval == C_OK) ? 0 : 1);
} else {
@@ -2561,7 +2561,7 @@ int rdbSaveToSlavesSockets(rdbSaveInfo *rsi) {
/* Create the child process. */
openChildInfoPipe();
- if ((childpid = redisFork()) == 0) {
+ if ((childpid = redisFork(CHILD_TYPE_RDB)) == 0) {
/* Child */
int retval, dummy;
rio rdb;
@@ -2576,7 +2576,7 @@ int rdbSaveToSlavesSockets(rdbSaveInfo *rsi) {
retval = C_ERR;
if (retval == C_OK) {
- sendChildCOWInfo(CHILD_INFO_TYPE_RDB, "RDB");
+ sendChildCOWInfo(CHILD_TYPE_RDB, "RDB");
}
rioFreeFd(&rdb);
diff --git a/src/redismodule.h b/src/redismodule.h
index 56011fae0..c0eedc221 100644
--- a/src/redismodule.h
+++ b/src/redismodule.h
@@ -112,6 +112,8 @@
#define REDISMODULE_CTX_FLAGS_ACTIVE_CHILD (1<<18)
/* The next EXEC will fail due to dirty CAS (touched keys). */
#define REDISMODULE_CTX_FLAGS_MULTI_DIRTY (1<<19)
+/* Redis is currently running inside background child process. */
+#define REDISMODULE_CTX_FLAGS_IS_CHILD (1<<20)
/* Keyspace changes notification classes. Every class is associated with a
* character for configuration purposes.
diff --git a/src/scripting.c b/src/scripting.c
index fdccb5db7..c8ff51b91 100644
--- a/src/scripting.c
+++ b/src/scripting.c
@@ -1858,7 +1858,7 @@ void ldbSendLogs(void) {
int ldbStartSession(client *c) {
ldb.forked = (c->flags & CLIENT_LUA_DEBUG_SYNC) == 0;
if (ldb.forked) {
- pid_t cp = redisFork();
+ pid_t cp = redisFork(CHILD_TYPE_LDB);
if (cp == -1) {
addReplyError(c,"Fork() failed: can't run EVAL in debugging mode.");
return 0;
diff --git a/src/server.c b/src/server.c
index 1ce20334c..3363d476f 100644
--- a/src/server.c
+++ b/src/server.c
@@ -2886,6 +2886,7 @@ void initServer(void) {
server.aof_state = server.aof_enabled ? AOF_ON : AOF_OFF;
server.hz = server.config_hz;
server.pid = getpid();
+ server.in_fork_child = CHILD_TYPE_NONE;
server.main_thread_id = pthread_self();
server.current_client = NULL;
server.fixed_time_expire = 0;
@@ -4989,7 +4990,8 @@ void removeSignalHandlers(void) {
* accepting writes because of a write error condition. */
static void sigKillChildHandler(int sig) {
UNUSED(sig);
- serverLogFromHandler(LL_WARNING, "Received SIGUSR1 in child, exiting now.");
+ int level = server.in_fork_child == CHILD_TYPE_MODULE? LL_VERBOSE: LL_WARNING;
+ serverLogFromHandler(level, "Received SIGUSR1 in child, exiting now.");
exitFromChild(SERVER_CHILD_NOERROR_RETVAL);
}
@@ -5015,11 +5017,13 @@ void closeClildUnusedResourceAfterFork() {
close(server.cluster_config_file_lock_fd); /* don't care if this fails */
}
-int redisFork() {
+/* purpose is one of CHILD_TYPE_ types */
+int redisFork(int purpose) {
int childpid;
long long start = ustime();
if ((childpid = fork()) == 0) {
/* Child */
+ server.in_fork_child = purpose;
setOOMScoreAdj(CONFIG_OOM_BGCHILD);
setupChildSignalHandlers();
closeClildUnusedResourceAfterFork();
diff --git a/src/server.h b/src/server.h
index 1025b1654..7d27626a7 100644
--- a/src/server.h
+++ b/src/server.h
@@ -1046,9 +1046,11 @@ struct clusterState;
#endif
#define CHILD_INFO_MAGIC 0xC17DDA7A12345678LL
-#define CHILD_INFO_TYPE_RDB 0
-#define CHILD_INFO_TYPE_AOF 1
-#define CHILD_INFO_TYPE_MODULE 3
+#define CHILD_TYPE_NONE 0
+#define CHILD_TYPE_RDB 1
+#define CHILD_TYPE_AOF 2
+#define CHILD_TYPE_LDB 3
+#define CHILD_TYPE_MODULE 4
struct redisServer {
/* General */
@@ -1062,6 +1064,7 @@ struct redisServer {
the actual 'hz' field value if dynamic-hz
is enabled. */
int hz; /* serverCron() calls frequency in hertz */
+ int in_fork_child; /* indication that this is a fork child */
redisDb *db;
dict *commands; /* Command table */
dict *orig_commands; /* Command table before command renaming. */
@@ -1904,7 +1907,7 @@ void sendChildInfo(int process_type);
void receiveChildInfo(void);
/* Fork helpers */
-int redisFork();
+int redisFork(int type);
int hasActiveChildProcess();
void sendChildCOWInfo(int ptype, char *pname);