xlog: add request details to panic message for broken LSN

Aid the debugging of replication issues related to out-of-order
requests. Adds the details of request/tuple to the diagnostic
message whenever possible.

Closes #3105

src/box/applier.cc

@@ -336,8 +336,7 @@ applier_join(struct applier *applier)
 		coio_read_xrow(coio, ibuf, &row);
 		applier->last_row_time = ev_monotonic_now(loop());
 		if (iproto_type_is_dml(row.type)) {
-			vclock_follow(&replicaset.vclock, row.replica_id,
-				      row.lsn);
+			vclock_follow_xrow(&replicaset.vclock, &row);
 			xstream_write_xc(applier->subscribe_stream, &row);
 		} else if (row.type == IPROTO_OK) {
 			/*
@@ -503,8 +502,7 @@ applier_subscribe(struct applier *applier)
 			 * the row is skipped when the replication
 			 * is resumed.
 			 */
-			vclock_follow(&replicaset.vclock, row.replica_id,
-				      row.lsn);
+			vclock_follow_xrow(&replicaset.vclock, &row);
 			struct replica *replica = replica_by_id(row.replica_id);
 			struct latch *latch = (replica ? &replica->order_latch :
 					       &replicaset.applier.order_latch);

src/box/recovery.cc

@@ -135,7 +135,7 @@ recovery_scan(struct recovery *r, struct vclock *end_vclock)
 		return;
 	struct xrow_header row;
 	while (xlog_cursor_next(&cursor, &row, true) == 0)
-		vclock_follow(end_vclock, row.replica_id, row.lsn);
+		vclock_follow_xrow(end_vclock, &row);
 	xlog_cursor_close(&cursor, false);
 }
 
@@ -266,7 +266,7 @@ recover_xlog(struct recovery *r, struct xstream *stream,
 		 * in case of forced recovery, when we skip the
 		 * failed row anyway.
 		 */
-		vclock_follow(&r->vclock,  row.replica_id, row.lsn);
+		vclock_follow_xrow(&r->vclock, &row);
 		if (xstream_write(stream, &row) == 0) {
 			++row_count;
 			if (row_count % 100000 == 0)

src/box/relay.cc

@@ -676,6 +676,13 @@ relay_send_row(struct xstream *stream, struct xrow_header *packet)
 	if (packet->replica_id != relay->replica->id ||
 	    packet->lsn <= vclock_get(&relay->local_vclock_at_subscribe,
 				      packet->replica_id)) {
+		struct errinj *inj = errinj(ERRINJ_RELAY_BREAK_LSN,
+					    ERRINJ_INT);
+		if (inj != NULL && packet->lsn == inj->iparam) {
+			packet->lsn = inj->iparam - 1;
+			say_warn("injected broken lsn: %lld",
+				 (long long) packet->lsn);
+		}
 		relay_send(relay, packet);
 	}
 }

src/box/vclock.c

@@ -42,13 +42,7 @@ vclock_follow(struct vclock *vclock, uint32_t replica_id, int64_t lsn)
 	assert(lsn >= 0);
 	assert(replica_id < VCLOCK_MAX);
 	int64_t prev_lsn = vclock->lsn[replica_id];
-	if (lsn <= prev_lsn) {
-		/* Never confirm LSN out of order. */
-		panic("LSN for %u is used twice or COMMIT order is broken: "
-		      "confirmed: %lld, new: %lld",
-		      (unsigned) replica_id,
-		      (long long) prev_lsn, (long long) lsn);
-	}
+	assert(lsn > prev_lsn);
 	/* Easier add each time than check. */
 	vclock->map |= 1 << replica_id;
 	vclock->lsn[replica_id] = lsn;

src/box/vclock.h

@@ -199,6 +199,14 @@ vclock_sum(const struct vclock *vclock)
 	return vclock->signature;
 }
 
+/**
+ * Update vclock with the next LSN value for given replica id.
+ *
+ * @param vclock Vector clock.
+ * @param replica_id Replica identifier.
+ * @param lsn Next lsn.
+ * @return previous lsn value.
+ */
 int64_t
 vclock_follow(struct vclock *vclock, uint32_t replica_id, int64_t lsn);
 

src/box/wal.c

@@ -186,6 +186,12 @@ xlog_write_entry(struct xlog *l, struct journal_entry *entry)
 	struct xrow_header **row = entry->rows;
 	for (; row < entry->rows + entry->n_rows; row++) {
 		(*row)->tm = ev_now(loop());
+		struct errinj *inj = errinj(ERRINJ_WAL_BREAK_LSN, ERRINJ_INT);
+		if (inj != NULL && inj->iparam == (*row)->lsn) {
+			(*row)->lsn = inj->iparam - 1;
+			say_warn("injected broken lsn: %lld",
+				 (long long) (*row)->lsn);
+		}
 		if (xlog_write_row(l, *row) < 0) {
 			/*
 			 * Rollback all un-written rows
@@ -652,8 +658,7 @@ wal_assign_lsn(struct wal_writer *writer, struct xrow_header **row,
 			(*row)->lsn = vclock_inc(&writer->vclock, instance_id);
 			(*row)->replica_id = instance_id;
 		} else {
-			vclock_follow(&writer->vclock, (*row)->replica_id,
-				      (*row)->lsn);
+			vclock_follow_xrow(&writer->vclock, *row);
 		}
 	}
 }
@@ -878,9 +883,8 @@ wal_write(struct journal *journal, struct journal_entry *entry)
 				 */
 				if (vclock_get(&replicaset.vclock,
 					       instance_id) < (*last)->lsn) {
-					vclock_follow(&replicaset.vclock,
-						      instance_id,
-						      (*last)->lsn);
+					vclock_follow_xrow(&replicaset.vclock,
+							   *last);
 				}
 				break;
 			}

src/box/xrow.h

@@ -522,6 +522,37 @@ xrow_to_iovec(const struct xrow_header *row, struct iovec *out);
 void
 xrow_decode_error(struct xrow_header *row);
 
+/**
+ * Update vclock with the next LSN value for given replica id.
+ * The function will cause panic if the next LSN happens to be
+ * out of order. The details of provided row are included into
+ * diagnostic message.
+ *
+ * @param vclock Vector clock.
+ * @param row Data row.
+ * @return Previous LSN value.
+ */
+static inline int64_t
+vclock_follow_xrow(struct vclock* vclock, const struct xrow_header *row)
+{
+	assert(row);
+	assert(row->replica_id < VCLOCK_MAX);
+	if (row->lsn <= vclock->lsn[row->replica_id]) {
+		struct request req;
+		const char *req_str = "n/a";
+		if (xrow_decode_dml((struct xrow_header *)row, &req, 0) == 0)
+			req_str = request_str(&req);
+		/* Never confirm LSN out of order. */
+		panic("LSN for %u is used twice or COMMIT order is broken: "
+		      "confirmed: %lld, new: %lld, req: %s",
+		      (unsigned) row->replica_id,
+		      (long long) vclock->lsn[row->replica_id],
+		      (long long) row->lsn,
+		      req_str);
+	}
+	return vclock_follow(vclock, row->replica_id, row->lsn);
+}
+
 #if defined(__cplusplus)
 } /* extern "C" */
 

src/errinj.h

@@ -118,6 +118,8 @@ struct errinj {
 	_(ERRINJ_VY_LOG_FILE_RENAME, ERRINJ_BOOL, {.bparam = false}) \
 	_(ERRINJ_VY_RUN_FILE_RENAME, ERRINJ_BOOL, {.bparam = false}) \
 	_(ERRINJ_VY_INDEX_FILE_RENAME, ERRINJ_BOOL, {.bparam = false}) \
+	_(ERRINJ_RELAY_BREAK_LSN, ERRINJ_INT, {.iparam = -1}) \
+	_(ERRINJ_WAL_BREAK_LSN, ERRINJ_INT, {.iparam = -1}) \
 
 ENUM0(errinj_id, ERRINJ_LIST);
 extern struct errinj errinjs[];

test/box/errinj.result

@@ -58,8 +58,12 @@ errinj.info()
     state: 0
   ERRINJ_XLOG_META:
     state: false
+  ERRINJ_WAL_BREAK_LSN:
+    state: -1
   ERRINJ_WAL_WRITE_DISK:
     state: false
+  ERRINJ_RELAY_BREAK_LSN:
+    state: -1
   ERRINJ_VY_LOG_FILE_RENAME:
     state: false
   ERRINJ_VY_RUN_WRITE:

test/xlog/panic_on_broken_lsn.result

@@ -0,0 +1,187 @@
+-- Issue 3105: Test logging of request with broken lsn before panicking
+-- Two cases are covered: Recovery and Joining a new replica
+env = require('test_run')
+---
+...
+test_run = env.new()
+---
+...
+test_run:cleanup_cluster()
+---
+...
+fio = require('fio')
+---
+...
+test_run:cmd("setopt delimiter ';'")
+---
+- true
+...
+function grep_file_tail(filepath, bytes, pattern)
+    local fh = fio.open(filepath, {'O_RDONLY'})
+    local size = fh:seek(0, 'SEEK_END')
+    if size < bytes then
+        bytes = size
+    end
+    fh:seek(-bytes, 'SEEK_END')
+    local line = fh:read(bytes)
+    fh:close()
+    return string.match(line, pattern)
+end;
+---
+...
+test_run:cmd("setopt delimiter ''");
+---
+- true
+...
+-- Testing case of panic on recovery
+test_run:cmd('create server panic with script="xlog/panic.lua"')
+---
+- true
+...
+test_run:cmd('start server panic')
+---
+- true
+...
+test_run:switch('panic')
+---
+- true
+...
+box.space._schema:replace{"t0", "v0"}
+---
+- ['t0', 'v0']
+...
+lsn = box.info.vclock[1]
+---
+...
+box.error.injection.set("ERRINJ_WAL_BREAK_LSN", lsn + 1)
+---
+- ok
+...
+box.space._schema:replace{"t0", "v1"}
+---
+- ['t0', 'v1']
+...
+box.error.injection.set("ERRINJ_WAL_BREAK_LSN", -1)
+---
+- ok
+...
+test_run:switch('default')
+---
+- true
+...
+test_run:cmd('stop server panic')
+---
+- true
+...
+dirname = fio.pathjoin(fio.cwd(), "panic")
+---
+...
+xlogs = fio.glob(dirname .. "/*.xlog")
+---
+...
+fio.unlink(xlogs[#xlogs])
+---
+- true
+...
+test_run:cmd('start server panic with crash_expected=True')
+---
+- false
+...
+logpath = fio.pathjoin(fio.cwd(), 'panic.log')
+---
+...
+-- Check that log contains the mention of broken LSN and the request printout
+grep_file_tail(logpath, 256, "LSN for 1 is used twice or COMMIT order is broken: confirmed: 1, new: 1, req: {.*}")
+---
+- 'LSN for 1 is used twice or COMMIT order is broken: confirmed: 1, new: 1, req: {type:
+  ''REPLACE'', lsn: 1, space_id: 272, index_id: 0, tuple: ["t0", "v1"]}'
+...
+test_run:cmd('cleanup server panic')
+---
+- true
+...
+test_run:cmd('delete server panic')
+---
+- true
+...
+-- Testing case of panic on joining a new replica
+box.schema.user.grant('guest', 'replication')
+---
+...
+_ = box.schema.space.create('test')
+---
+...
+_ = box.space.test:create_index('pk')
+---
+...
+box.space.test:auto_increment{'v0'}
+---
+- [1, 'v0']
+...
+lsn = box.info.vclock[1]
+---
+...
+box.error.injection.set("ERRINJ_RELAY_BREAK_LSN", lsn + 1)
+---
+- ok
+...
+box.space.test:auto_increment{'v1'}
+---
+- [2, 'v1']
+...
+test_run:cmd('create server replica with rpl_master=default, script="xlog/replica.lua"')
+---
+- true
+...
+test_run:cmd('start server replica with crash_expected=True')
+---
+- false
+...
+fiber = require('fiber')
+---
+...
+while box.info.replication == nil do fiber.sleep(0.001) end
+---
+...
+while box.info.replication[2].downstream.status ~= "stopped" do fiber.sleep(0.001) end
+---
+...
+box.error.injection.set("ERRINJ_RELAY_BREAK_LSN", -1)
+---
+- ok
+...
+logpath = fio.pathjoin(fio.cwd(), 'replica.log')
+---
+...
+-- Check that log contains the mention of broken LSN and the request printout
+test_run:cmd("push filter 'lsn: "..lsn..", space_id: [0-9]+' to 'lsn: <lsn>, space_id: <space_id>'")
+---
+- true
+...
+test_run:cmd("push filter 'confirmed: "..lsn..", new: "..lsn.."' to '<lsn>'")
+---
+- true
+...
+grep_file_tail(logpath, 256, "(LSN for 1 is used twice or COMMIT order is broken: confirmed: "..lsn..", new: "..lsn.."), req: ({.*})")
+---
+- 'LSN for 1 is used twice or COMMIT order is broken: <lsn>'
+- '{type: ''INSERT'', lsn: <lsn>, space_id: <space_id>, index_id: 0, tuple: [2, "v1"]}'
+...
+test_run:cmd("clear filter")
+---
+- true
+...
+test_run:cmd('cleanup server replica')
+---
+- true
+...
+test_run:cmd('delete server replica')
+---
+- true
+...
+box.space.test:drop()
+---
+...
+box.schema.user.revoke('guest', 'replication')
+---
+...