gvsafronov/futriix
1
0
Fork 0
Code Issues Pull Requests Actions 3 Packages Projects Releases Wiki Activity

Merge pull request #6144 from madolson/dev-unstable-cluster-down

Browse Source 
Add configuration option for allowing reads on cluster down
This commit is contained in:
Salvatore Sanfilippo 2019-12-17 09:15:20 +01:00 committed by GitHub
commit f3d67b3842
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
7 changed files with 69 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

16
redis.conf
View File

@ -1194,6 +1194,22 @@ lua-time-limit 5000
#
# cluster-replica-no-failover no
# This option, when set to yes, allows nodes to serve read traffic while the
# the cluster is in a down state, as long as it believes it owns the slots.
#
# This is useful for two cases. The first case is for when an application
# doesn't require consistency of data during node failures or network partitions.
# One example of this is a cache, where as long as the node has the data it
# should be able to serve it.
#
# The second use case is for configurations that don't meet the recommended
# three shards but want to enable cluster mode and scale later. A
# master outage in a 1 or 2 shard configuration causes a read/write outage to the
# entire cluster without this option set, with it set there is only a write outage.
# Without a quorum of masters, slot ownership will not change automatically.
#
# cluster-allow-reads-when-down no
# In order to setup your cluster make sure to read the documentation
# available at http://redis.io web site.

26
src/cluster.c
View File

@ -5476,8 +5476,8 @@ void readwriteCommand(client *c) {
* already "down" but it is fragile to rely on the update of the global state,
* so we also handle it here.
*
* CLUSTER_REDIR_DOWN_STATE if the cluster is down but the user attempts to
* execute a command that addresses one or more keys. */
* CLUSTER_REDIR_DOWN_STATE and CLUSTER_REDIR_DOWN_RO_STATE if the cluster is
* down but the user attempts to execute a command that addresses one or more keys. */
clusterNode *getNodeByQuery(client *c, struct redisCommand *cmd, robj **argv, int argc, int *hashslot, int *error_code) {
clusterNode *n = NULL;
robj *firstkey = NULL;
@ -5595,10 +5595,19 @@ clusterNode *getNodeByQuery(client *c, struct redisCommand *cmd, robj **argv, in
* without redirections or errors in all the cases. */
if (n == NULL) return myself;
/* Cluster is globally down but we got keys? We can't serve the request. */
/* Cluster is globally down but we got keys? We only serve the request
* if it is a read command and when allow_reads_when_down is enabled. */
if (server.cluster->state != CLUSTER_OK) {
if (error_code) *error_code = CLUSTER_REDIR_DOWN_STATE;
return NULL;
if (!server.cluster_allow_reads_when_down) {
if (error_code) *error_code = CLUSTER_REDIR_DOWN_STATE;
return NULL;
}
if (!(cmd->flags & CMD_READONLY) && !(cmd->proc == evalCommand)
&& !(cmd->proc == evalShaCommand)) {
if (error_code) *error_code = CLUSTER_REDIR_DOWN_RO_STATE;
return NULL;
}
}
/* Return the hashslot by reference. */
@ -5667,6 +5676,8 @@ void clusterRedirectClient(client *c, clusterNode *n, int hashslot, int error_co
addReplySds(c,sdsnew("-TRYAGAIN Multiple keys request during rehashing of slot\r\n"));
} else if (error_code == CLUSTER_REDIR_DOWN_STATE) {
addReplySds(c,sdsnew("-CLUSTERDOWN The cluster is down\r\n"));
} else if (error_code == CLUSTER_REDIR_DOWN_RO_STATE) {
addReplySds(c,sdsnew("-CLUSTERDOWN The cluster is down and only accepts read commands\r\n"));
} else if (error_code == CLUSTER_REDIR_DOWN_UNBOUND) {
addReplySds(c,sdsnew("-CLUSTERDOWN Hash slot not served\r\n"));
} else if (error_code == CLUSTER_REDIR_MOVED ||
@ -5701,7 +5712,10 @@ int clusterRedirectBlockedClientIfNeeded(client *c) {
dictEntry *de;
dictIterator *di;
/* If the cluster is down, unblock the client with the right error. */
/* If the cluster is down, unblock the client with the right error.
* If the cluster is configured to allow reads on cluster down, we
* still want to emit this error since a write will be required
* to unblock them which may never come. */
if (server.cluster->state == CLUSTER_FAIL) {
clusterRedirectClient(c,NULL,0,CLUSTER_REDIR_DOWN_STATE);
return 1;

1
src/cluster.h
View File

@ -29,6 +29,7 @@
#define CLUSTER_REDIR_MOVED 4 /* -MOVED redirection required. */
#define CLUSTER_REDIR_DOWN_STATE 5 /* -CLUSTERDOWN, global state. */
#define CLUSTER_REDIR_DOWN_UNBOUND 6 /* -CLUSTERDOWN, unbound slot. */
#define CLUSTER_REDIR_DOWN_RO_STATE 7 /* -CLUSTERDOWN, allow reads. */
struct clusterNode;

2
src/config.c
View File

@ -2166,6 +2166,8 @@ standardConfig configs[] = {
createBoolConfig("syslog-enabled", NULL, IMMUTABLE_CONFIG, server.syslog_enabled, 0, NULL, NULL),
createBoolConfig("cluster-enabled", NULL, IMMUTABLE_CONFIG, server.cluster_enabled, 0, NULL, NULL),
createBoolConfig("appendonly", NULL, MODIFIABLE_CONFIG, server.aof_enabled, 0, NULL, updateAppendonly),
createBoolConfig("cluster-allow-reads-when-down", NULL, MODIFIABLE_CONFIG, server.cluster_allow_reads_when_down, 0, NULL, NULL),
/* String Configs */
createStringConfig("aclfile", NULL, IMMUTABLE_CONFIG, ALLOW_EMPTY_STRING, server.acl_filename, "", NULL, NULL),

14
src/module.c
View File

@ -3174,6 +3174,9 @@ fmterr:
* EINVAL: wrong command arity.
* ENOENT: command does not exist.
* EPERM: operation in Cluster instance with key in non local slot.
* EROFS: operation in Cluster instance when a write command is sent
* in a readonly state.
* ENETDOWN: operation in Cluster instance when cluster is down.
*
* This API is documented here: https://redis.io/topics/modules-intro
*/
@ -3231,13 +3234,20 @@ RedisModuleCallReply *RM_Call(RedisModuleCtx *ctx, const char *cmdname, const ch
* trying to access non-local keys, with the exception of commands
* received from our master. */
if (server.cluster_enabled && !(ctx->client->flags & CLIENT_MASTER)) {
int error_code;
/* Duplicate relevant flags in the module client. */
c->flags &= ~(CLIENT_READONLY|CLIENT_ASKING);
c->flags |= ctx->client->flags & (CLIENT_READONLY|CLIENT_ASKING);
if (getNodeByQuery(c,c->cmd,c->argv,c->argc,NULL,NULL) !=
if (getNodeByQuery(c,c->cmd,c->argv,c->argc,NULL,&error_code) !=
server.cluster->myself)
{
errno = EPERM;
if (error_code == CLUSTER_REDIR_DOWN_RO_STATE) {
errno = EROFS;
} else if (error_code == CLUSTER_REDIR_DOWN_STATE) {
errno = ENETDOWN;
} else {
errno = EPERM;
}
goto cleanup;
}
}

20
src/scripting.c
View File

@ -679,15 +679,27 @@ int luaRedisGenericCommand(lua_State *lua, int raise_error) {
if (server.cluster_enabled && !server.loading &&
!(server.lua_caller->flags & CLIENT_MASTER))
{
int error_code;
/* Duplicate relevant flags in the lua client. */
c->flags &= ~(CLIENT_READONLY|CLIENT_ASKING);
c->flags |= server.lua_caller->flags & (CLIENT_READONLY|CLIENT_ASKING);
if (getNodeByQuery(c,c->cmd,c->argv,c->argc,NULL,NULL) !=
if (getNodeByQuery(c,c->cmd,c->argv,c->argc,NULL,&error_code) !=
server.cluster->myself)
{
luaPushError(lua,
"Lua script attempted to access a non local key in a "
"cluster node");
if (error_code == CLUSTER_REDIR_DOWN_RO_STATE) {
luaPushError(lua,
"Lua script attempted to execute a write command while the "
"cluster is down and readonly");
} else if (error_code == CLUSTER_REDIR_DOWN_STATE) {
luaPushError(lua,
"Lua script attempted to execute a command while the "
"cluster is down");
} else {
luaPushError(lua,
"Lua script attempted to access a non local key in a "
"cluster node");
}
goto cleanup;
}
}

2
src/server.h
View File

@ -1334,6 +1334,8 @@ struct redisServer {
to set in order to suppress certain
native Redis Cluster features. Check the
REDISMODULE_CLUSTER_FLAG_*. */
int cluster_allow_reads_when_down; /* Are reads allowed when the cluster
is down? */
/* Scripting */
lua_State *lua; /* The Lua interpreter. We use just one for all clients */
client *lua_client; /* The "fake client" to query Redis from Lua */