[tarantool-patches] [PATCH v3 2/2] replication: force gc to clean xdir on ENOSPC err

[Konstantin Belyavskiy <k.belyavskiy@tarantool.org>]

Garbage collector do not delete xlog unless replica do not notify
master with newer vclock. This can lead to running out of disk
space error and this is not right behaviour since it will stop the
master.
Fix it by forcing gc to clean xlogs for replica with highest lag.
Add an error injection and a test.

Changes in V2:
- Promoting error from 'wal' thread to 'tx' thread via 'cpipe'.
Changes in V3:
- Exclude 'tx' to 'tx_prio' rename with a separate patch.
- Delete consumers and only for replicas (but not backup process).
- Use timestamp to prevent gc from running more then one time in
  case of multiple failures.
- other small fixes according to code review.

Closes #3397
---
 src/box/box.cc                                    |   1 +
 src/box/gc.c                                      |  51 +++++++++++
 src/box/gc.h                                      |  16 ++++
 src/box/relay.cc                                  |   1 +
 src/box/wal.cc                                    |  21 +++++
 src/errinj.h                                      |   1 +
 src/fio.c                                         |   7 ++
 test/box/errinj.result                            |   2 +
 test/replication/force_gc_on_err_nospace.result   | 107 ++++++++++++++++++++++
 test/replication/force_gc_on_err_nospace.test.lua |  38 ++++++++
 test/replication/suite.ini                        |   2 +-
 11 files changed, 246 insertions(+), 1 deletion(-)
 create mode 100644 test/replication/force_gc_on_err_nospace.result
 create mode 100644 test/replication/force_gc_on_err_nospace.test.lua

diff --git a/src/box/box.cc b/src/box/box.cc
index e3eb2738f..ba894c33a 100644
--- a/src/box/box.cc
+++ b/src/box/box.cc
@@ -1370,6 +1370,7 @@ box_process_join(struct ev_io *io, struct xrow_header *header)
 	replica = replica_by_uuid(&instance_uuid);
 	assert(replica != NULL);
 	replica->gc = gc;
+	gc_consumer_set_replica(gc, replica);
 	gc_guard.is_active = false;

 	/* Remember master's vclock after the last request */
diff --git a/src/box/gc.c b/src/box/gc.c
index 12e68f3dc..904496366 100644
--- a/src/box/gc.c
+++ b/src/box/gc.c
@@ -35,6 +35,7 @@
 #include <stdint.h>
 #include <stdlib.h>
 #include <string.h>
+#include <time.h>

 #define RB_COMPACT 1
 #include <small/rb.h>
@@ -61,6 +62,8 @@ struct gc_consumer {
 	char *name;
 	/** The vclock signature tracked by this consumer. */
 	int64_t signature;
+	/** Replica associated with consumer (if any). */
+	struct replica *replica;
 };

 typedef rb_tree(struct gc_consumer) gc_tree_t;
@@ -123,10 +126,18 @@ gc_consumer_new(const char *name, int64_t signature)
 	return consumer;
 }

+void
+gc_consumer_set_replica(struct gc_consumer *gc, struct replica *replica)
+{
+	gc->replica = replica;
+}
+
 /** Free a consumer object. */
 static void
 gc_consumer_delete(struct gc_consumer *consumer)
 {
+	if (consumer->replica != NULL)
+		consumer->replica->gc = NULL;
 	free(consumer->name);
 	TRASH(consumer);
 	free(consumer);
@@ -216,6 +227,46 @@ gc_set_checkpoint_count(int checkpoint_count)
 	gc.checkpoint_count = checkpoint_count;
 }

+void
+gc_xdir_clean_notify()
+{
+	/*
+	 * Compare the current time with the time of the last run.
+	 * This is needed in case of multiple failures to prevent
+	 * from deleting all replicas.
+	 */
+	static int prev_time = 0;
+	int cur_time = time(NULL);
+	if (cur_time - prev_time < 1)
+		return;
+	prev_time = cur_time;
+	/**
+	 * Mark consumer with least recent vclock as "dead" and
+	 * invoke garbage collection. If nothing to delete find
+	 * next alive consumer etc. Originally created for
+	 * cases with running out of disk space because of
+	 * disconnected replica.
+	 */
+	struct gc_consumer *leftmost =
+	    gc_tree_first(&gc.consumers);
+	/*
+	 * Exit if no consumers left or if this consumer is
+	 * not associated with replica (backup for example).
+	 */
+	if (leftmost == NULL || leftmost->replica == NULL)
+		return;
+	int64_t signature = leftmost->signature;
+	while (true) {
+		gc_consumer_unregister(leftmost);
+		leftmost = gc_tree_first(&gc.consumers);
+		if (leftmost == NULL || leftmost->replica == NULL ||
+		    leftmost->signature > signature) {
+			gc_run();
+			return;
+		}
+	}
+}
+
 struct gc_consumer *
 gc_consumer_register(const char *name, int64_t signature)
 {
diff --git a/src/box/gc.h b/src/box/gc.h
index 634ce6d38..15d966f54 100644
--- a/src/box/gc.h
+++ b/src/box/gc.h
@@ -31,9 +31,12 @@
  * SUCH DAMAGE.
  */

+#include <stdbool.h>
 #include <stddef.h>
 #include <stdint.h>

+#include "replication.h"
+
 #if defined(__cplusplus)
 extern "C" {
 #endif /* defined(__cplusplus) */
@@ -81,6 +84,12 @@ gc_set_checkpoint_count(int checkpoint_count);
 struct gc_consumer *
 gc_consumer_register(const char *name, int64_t signature);

+/**
+ * Bind consumer with associated replica (if any).
+ */
+void
+gc_consumer_set_replica(struct gc_consumer *gc, struct replica *replica);
+
 /**
  * Unregister a consumer and invoke garbage collection
  * if needed.
@@ -88,6 +97,13 @@ gc_consumer_register(const char *name, int64_t signature);
 void
 gc_consumer_unregister(struct gc_consumer *consumer);

+/**
+ * Notify gc to clean xdir because of running out
+ * of disk space.
+ */
+void
+gc_xdir_clean_notify();
+
 /**
  * Advance the vclock signature tracked by a consumer and
  * invoke garbage collection if needed.
diff --git a/src/box/relay.cc b/src/box/relay.cc
index d2ceaf110..c317775a4 100644
--- a/src/box/relay.cc
+++ b/src/box/relay.cc
@@ -535,6 +535,7 @@ relay_subscribe(int fd, uint64_t sync, struct replica *replica,
 			vclock_sum(replica_clock));
 		if (replica->gc == NULL)
 			diag_raise();
+		gc_consumer_set_replica(replica->gc, replica);
 	}

 	struct relay relay;
diff --git a/src/box/wal.cc b/src/box/wal.cc
index 93c350e1f..8dc973de8 100644
--- a/src/box/wal.cc
+++ b/src/box/wal.cc
@@ -41,6 +41,7 @@
 #include "cbus.h"
 #include "coio_task.h"
 #include "replication.h"
+#include "gc.h"


 const char *wal_mode_STRS[] = { "none", "write", "fsync", NULL };
@@ -64,6 +65,8 @@ struct wal_thread {
 	 * priority pipe and DOES NOT support yield.
 	 */
 	struct cpipe tx_prio_pipe;
+	/** Return pipe from 'wal' to tx' */
+	struct cpipe tx_pipe;
 };

 /*
@@ -584,6 +587,13 @@ wal_assign_lsn(struct wal_writer *writer, struct xrow_header **row,
 	}
 }

+static void
+gc_status_update(struct cmsg *msg)
+{
+	gc_xdir_clean_notify();
+	delete(msg);
+}
+
 static void
 wal_write_to_disk(struct cmsg *msg)
 {
@@ -655,6 +665,15 @@ done:
 		/* Until we can pass the error to tx, log it and clear. */
 		error_log(error);
 		diag_clear(diag_get());
+		if (errno == ENOSPC) {
+			struct cmsg *msg =
+			    (struct cmsg*)calloc(1, sizeof(struct cmsg));
+			static const struct cmsg_hop route[] = {
+				{gc_status_update, NULL}
+			};
+			cmsg_init(msg, route);
+			cpipe_push(&wal_thread.tx_pipe, msg);
+		}
 	}
 	/*
 	 * We need to start rollback from the first request
@@ -695,6 +714,7 @@ wal_thread_f(va_list ap)
 	 * even when tx fiber pool is used up by net messages.
 	 */
 	cpipe_create(&wal_thread.tx_prio_pipe, "tx_prio");
+	cpipe_create(&wal_thread.tx_pipe, "tx");

 	cbus_loop(&endpoint);

@@ -707,6 +727,7 @@ wal_thread_f(va_list ap)
 		xlog_close(&vy_log_writer.xlog, false);

 	cpipe_destroy(&wal_thread.tx_prio_pipe);
+	cpipe_destroy(&wal_thread.tx_pipe);
 	return 0;
 }

diff --git a/src/errinj.h b/src/errinj.h
index 895d938d5..11f1b7fdc 100644
--- a/src/errinj.h
+++ b/src/errinj.h
@@ -112,6 +112,7 @@ struct errinj {
 	_(ERRINJ_LOG_ROTATE, ERRINJ_BOOL, {.bparam = false}) \
 	_(ERRINJ_SNAP_COMMIT_DELAY, ERRINJ_BOOL, {.bparam = 0}) \
 	_(ERRINJ_SNAP_WRITE_ROW_TIMEOUT, ERRINJ_DOUBLE, {.dparam = 0}) \
+	_(ERRINJ_NO_DISK_SPACE, ERRINJ_BOOL, {.bparam = false}) \

 ENUM0(errinj_id, ERRINJ_LIST);
 extern struct errinj errinjs[];
diff --git a/src/fio.c b/src/fio.c
index b79d3d058..cdea11e87 100644
--- a/src/fio.c
+++ b/src/fio.c
@@ -29,6 +29,7 @@
  * SUCH DAMAGE.
  */
 #include "fio.h"
+#include "errinj.h"

 #include <sys/types.h>

@@ -141,6 +142,12 @@ fio_writev(int fd, struct iovec *iov, int iovcnt)
 	ssize_t nwr;
 restart:
 	nwr = writev(fd, iov, iovcnt);
+	/* Simulate running out of disk space to force the gc to clean logs. */
+	struct errinj *inj = errinj(ERRINJ_NO_DISK_SPACE, ERRINJ_BOOL);
+	if (inj != NULL && inj->bparam) {
+		errno = ENOSPC;
+		nwr = -1;
+	}
 	if (nwr < 0) {
 		if (errno == EINTR) {
 			errno = 0;
diff --git a/test/box/errinj.result b/test/box/errinj.result
index 21a949965..a28688436 100644
--- a/test/box/errinj.result
+++ b/test/box/errinj.result
@@ -56,6 +56,8 @@ errinj.info()
     state: false
   ERRINJ_VY_RUN_WRITE:
     state: false
+  ERRINJ_NO_DISK_SPACE:
+    state: false
   ERRINJ_VY_LOG_FLUSH_DELAY:
     state: false
   ERRINJ_SNAP_COMMIT_DELAY:
diff --git a/test/replication/force_gc_on_err_nospace.result b/test/replication/force_gc_on_err_nospace.result
new file mode 100644
index 000000000..904a36ddc
--- /dev/null
+++ b/test/replication/force_gc_on_err_nospace.result
@@ -0,0 +1,107 @@
+env = require('test_run')
+---
+...
+test_run = env.new()
+---
+...
+engine = test_run:get_cfg('engine')
+---
+...
+box.schema.user.grant('guest', 'read,write,execute', 'universe')
+---
+...
+s = box.schema.space.create('test', {engine = engine});
+---
+...
+index = s:create_index('primary', {type = 'tree'})
+---
+...
+errinj = box.error.injection
+---
+...
+fio = require('fio')
+---
+...
+box.schema.user.grant('guest', 'replication')
+---
+...
+test_run:cmd("create server replica with rpl_master=default, script='replication/replica.lua'")
+---
+- true
+...
+test_run:cmd("start server replica")
+---
+- true
+...
+test_run:cmd("switch replica")
+---
+- true
+...
+repl = box.cfg.replication
+---
+...
+box.cfg{replication = ""}
+---
+...
+test_run:cmd("switch default")
+---
+- true
+...
+for i = 1, 5 do s:insert{i} box.snapshot() end
+---
+...
+s:select()
+---
+- - [1]
+  - [2]
+  - [3]
+  - [4]
+  - [5]
+...
+#fio.glob(fio.pathjoin(fio.abspath("."), 'master/*.xlog'))
+---
+- 6
+...
+errinj.set("ERRINJ_NO_DISK_SPACE", true)
+---
+- ok
+...
+function insert(a) s:insert(a) end
+---
+...
+_, err = pcall(insert, {6})
+---
+...
+err:match("ailed to write")
+---
+- ailed to write
+...
+-- add a little timeout so gc could finish job
+require('fiber').sleep(0.01)
+---
+...
+#fio.glob(fio.pathjoin(fio.abspath("."), 'master/*.xlog'))
+---
+- 2
+...
+-- cleanup
+test_run:cmd("switch replica")
+---
+- true
+...
+test_run:cmd("restart server default with cleanup=1")
+---
+- true
+...
+test_run:cmd("switch default")
+---
+- true
+...
+test_run:cmd("stop server replica")
+---
+- true
+...
+test_run:cmd("cleanup server replica")
+---
+- true
+...
diff --git a/test/replication/force_gc_on_err_nospace.test.lua b/test/replication/force_gc_on_err_nospace.test.lua
new file mode 100644
index 000000000..fea4aa73b
--- /dev/null
+++ b/test/replication/force_gc_on_err_nospace.test.lua
@@ -0,0 +1,38 @@
+env = require('test_run')
+test_run = env.new()
+engine = test_run:get_cfg('engine')
+
+box.schema.user.grant('guest', 'read,write,execute', 'universe')
+
+s = box.schema.space.create('test', {engine = engine});
+index = s:create_index('primary', {type = 'tree'})
+
+errinj = box.error.injection
+fio = require('fio')
+
+box.schema.user.grant('guest', 'replication')
+test_run:cmd("create server replica with rpl_master=default, script='replication/replica.lua'")
+test_run:cmd("start server replica")
+
+test_run:cmd("switch replica")
+repl = box.cfg.replication
+box.cfg{replication = ""}
+test_run:cmd("switch default")
+
+for i = 1, 5 do s:insert{i} box.snapshot() end
+s:select()
+#fio.glob(fio.pathjoin(fio.abspath("."), 'master/*.xlog'))
+errinj.set("ERRINJ_NO_DISK_SPACE", true)
+function insert(a) s:insert(a) end
+_, err = pcall(insert, {6})
+err:match("ailed to write")
+-- add a little timeout so gc could finish job
+require('fiber').sleep(0.01)
+#fio.glob(fio.pathjoin(fio.abspath("."), 'master/*.xlog'))
+
+-- cleanup
+test_run:cmd("switch replica")
+test_run:cmd("restart server default with cleanup=1")
+test_run:cmd("switch default")
+test_run:cmd("stop server replica")
+test_run:cmd("cleanup server replica")
diff --git a/test/replication/suite.ini b/test/replication/suite.ini
index b489add58..1706cf697 100644
--- a/test/replication/suite.ini
+++ b/test/replication/suite.ini
@@ -3,7 +3,7 @@ core = tarantool
 script =  master.lua
 description = tarantool/box, replication
 disabled = consistent.test.lua
-release_disabled = catch.test.lua errinj.test.lua gc.test.lua before_replace.test.lua quorum.test.lua recover_missing_xlog.test.lua
+release_disabled = catch.test.lua errinj.test.lua force_gc_on_err_nospace.test.lua gc.test.lua before_replace.test.lua quorum.test.lua recover_missing_xlog.test.lua
 config = suite.cfg
 lua_libs = lua/fast_replica.lua
 long_run = prune.test.lua
--
2.14.3 (Apple Git-98)