Cluster: ability to prevent slaves from failing over their masters.

This commit, in some parts derived from PR #3041 which is no longer
possible to merge (because the user deleted the original branch),
implements the ability of slaves to have a special configuration
preventing that they try to start a failover when the master is failing.

There are multiple reasons for wanting this, and the feautre was
requested in issue #3021 time ago.

The differences between this patch and the original PR are the
following:

1. The flag is saved/loaded on the nodes configuration.
2. The 'myself' node is now flag-aware, the flag is updated as needed
   when the configuration is changed via CONFIG SET.
3. The flag name uses NOFAILOVER instead of NO_FAILOVER to be consistent
   with existing NOADDR.
4. The redis.conf documentation was rewritten.

Thanks to @deep011 for the original patch.
This commit is contained in:
antirez
2018-03-14 13:46:36 +01:00
parent 84b281209a
commit 432bf4770e
6 changed files with 70 additions and 2 deletions

View File

@ -16,6 +16,7 @@
#define CLUSTER_DEFAULT_NODE_TIMEOUT 15000
#define CLUSTER_DEFAULT_SLAVE_VALIDITY 10 /* Slave max data age factor. */
#define CLUSTER_DEFAULT_REQUIRE_FULL_COVERAGE 1
#define CLUSTER_DEFAULT_SLAVE_NO_FAILOVER 0 /* Failover by default. */
#define CLUSTER_FAIL_REPORT_VALIDITY_MULT 2 /* Fail report validity. */
#define CLUSTER_FAIL_UNDO_TIME_MULT 2 /* Undo fail if master is back. */
#define CLUSTER_FAIL_UNDO_TIME_ADD 10 /* Some additional time. */
@ -55,6 +56,7 @@ typedef struct clusterLink {
#define CLUSTER_NODE_NOADDR 64 /* We don't know the address of this node */
#define CLUSTER_NODE_MEET 128 /* Send a MEET message to this node */
#define CLUSTER_NODE_MIGRATE_TO 256 /* Master elegible for replica migration. */
#define CLUSTER_NODE_NOFAILOVER 512 /* Slave will not try to failver. */
#define CLUSTER_NODE_NULL_NAME "\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000"
#define nodeIsMaster(n) ((n)->flags & CLUSTER_NODE_MASTER)
@ -64,6 +66,7 @@ typedef struct clusterLink {
#define nodeWithoutAddr(n) ((n)->flags & CLUSTER_NODE_NOADDR)
#define nodeTimedOut(n) ((n)->flags & CLUSTER_NODE_PFAIL)
#define nodeFailed(n) ((n)->flags & CLUSTER_NODE_FAIL)
#define nodeCantFailover(n) ((n)->flags & CLUSTER_NODE_NOFAILOVER)
/* Reasons why a slave is not able to failover. */
#define CLUSTER_CANT_FAILOVER_NONE 0