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pglogical_apply.c
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pglogical_apply.c
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/*-------------------------------------------------------------------------
*
* pglogical_apply.c
* pglogical apply logic
*
* Copyright (c) 2015, PostgreSQL Global Development Group
*
* IDENTIFICATION
* pglogical.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "miscadmin.h"
#include "libpq-fe.h"
#include "pgstat.h"
#include "access/htup_details.h"
#include "access/xact.h"
#include "catalog/namespace.h"
#include "commands/dbcommands.h"
#include "commands/sequence.h"
#include "commands/tablecmds.h"
#include "commands/trigger.h"
#include "executor/executor.h"
#include "libpq/pqformat.h"
#include "mb/pg_wchar.h"
#include "nodes/makefuncs.h"
#include "nodes/parsenodes.h"
#include "optimizer/planner.h"
#ifdef XCP
#include "pgxc/pgxcnode.h"
#endif
#include "replication/origin.h"
#include "rewrite/rewriteHandler.h"
#include "storage/ipc.h"
#include "storage/lmgr.h"
#include "storage/proc.h"
#include "tcop/pquery.h"
#include "tcop/utility.h"
#include "utils/builtins.h"
#include "utils/int8.h"
#include "utils/jsonb.h"
#include "utils/lsyscache.h"
#include "utils/memutils.h"
#include "utils/snapmgr.h"
#include "pglogical_conflict.h"
#include "pglogical_executor.h"
#include "pglogical_node.h"
#include "pglogical_queue.h"
#include "pglogical_relcache.h"
#include "pglogical_repset.h"
#include "pglogical_rpc.h"
#include "pglogical_sync.h"
#include "pglogical_worker.h"
#include "pglogical_apply.h"
#include "pglogical_apply_heap.h"
#include "pglogical_apply_spi.h"
#include "pglogical.h"
void pglogical_apply_main(Datum main_arg);
static bool in_remote_transaction = false;
static XLogRecPtr remote_origin_lsn = InvalidXLogRecPtr;
static RepOriginId remote_origin_id = InvalidRepOriginId;
static TimeOffset apply_delay = 0;
static Oid QueueRelid = InvalidOid;
static List *SyncingTables = NIL;
PGLogicalApplyWorker *MyApplyWorker = NULL;
PGLogicalSubscription *MySubscription = NULL;
static PGconn *applyconn = NULL;
typedef struct PGLogicalApplyFunctions
{
pglogical_apply_begin_fn on_begin;
pglogical_apply_commit_fn on_commit;
pglogical_apply_insert_fn do_insert;
pglogical_apply_update_fn do_update;
pglogical_apply_delete_fn do_delete;
pglogical_apply_can_mi_fn can_multi_insert;
pglogical_apply_mi_add_tuple_fn multi_insert_add_tuple;
pglogical_apply_mi_finish_fn multi_insert_finish;
} PGLogicalApplyFunctions;
static PGLogicalApplyFunctions apply_api =
{
.on_begin = pglogical_apply_heap_begin,
.on_commit = pglogical_apply_heap_commit,
.do_insert = pglogical_apply_heap_insert,
.do_update = pglogical_apply_heap_update,
.do_delete = pglogical_apply_heap_delete,
.can_multi_insert = pglogical_apply_heap_can_mi,
.multi_insert_add_tuple = pglogical_apply_heap_mi_add_tuple,
.multi_insert_finish = pglogical_apply_heap_mi_finish
};
/* Number of tuples inserted after which we switch to multi-insert. */
#define MIN_MULTI_INSERT_TUPLES 5
static PGLogicalRelation *last_insert_rel = NULL;
static int last_insert_rel_cnt = 0;
static bool use_multi_insert = false;
typedef struct PGLFlushPosition
{
dlist_node node;
XLogRecPtr local_end;
XLogRecPtr remote_end;
} PGLFlushPosition;
dlist_head lsn_mapping = DLIST_STATIC_INIT(lsn_mapping);
typedef struct ApplyExecState
{
EState *estate;
EPQState epqstate;
ResultRelInfo *resultRelInfo;
TupleTableSlot *slot;
} ApplyExecState;
static void multi_insert_finish(void);
static void handle_queued_message(HeapTuple msgtup, bool tx_just_started);
static void handle_startup_param(const char *key, const char *value);
static bool parse_bool_param(const char *key, const char *value);
static void process_syncing_tables(XLogRecPtr end_lsn);
static void start_sync_worker(RangeVar *rv);
/*
* Check if given relation is in process of being synchronized.
*
* TODO: performance
*/
static bool
check_syncing_relation(const char *nspname, const char *relname)
{
return list_length(SyncingTables) &&
list_member(SyncingTables, makeRangeVar((char *)nspname, (char *)relname, -1));
}
static bool
ensure_transaction(void)
{
if (IsTransactionState())
{
if (CurrentMemoryContext != MessageContext)
MemoryContextSwitchTo(MessageContext);
return false;
}
StartTransactionCommand();
apply_api.on_begin();
MemoryContextSwitchTo(MessageContext);
return true;
}
static void
handle_begin(StringInfo s)
{
XLogRecPtr commit_lsn;
TimestampTz commit_time;
TransactionId remote_xid;
pglogical_read_begin(s, &commit_lsn, &commit_time, &remote_xid);
replorigin_session_origin_timestamp = commit_time;
replorigin_session_origin_lsn = commit_lsn;
remote_origin_id = InvalidRepOriginId;
/* don't want the overhead otherwise */
if (apply_delay > 0)
{
TimestampTz current;
current = GetCurrentIntegerTimestamp();
/* ensure no weirdness due to clock drift */
if (current > replorigin_session_origin_timestamp)
{
long sec;
int usec;
current = TimestampTzPlusMilliseconds(current,
-apply_delay);
TimestampDifference(current, replorigin_session_origin_timestamp,
&sec, &usec);
/* FIXME: deal with overflow? */
pg_usleep(usec + (sec * USECS_PER_SEC));
}
}
in_remote_transaction = true;
pgstat_report_activity(STATE_RUNNING, NULL);
}
/*
* Handle COMMIT message.
*/
static void
handle_commit(StringInfo s)
{
XLogRecPtr commit_lsn;
XLogRecPtr end_lsn;
TimestampTz commit_time;
pglogical_read_commit(s, &commit_lsn, &end_lsn, &commit_time);
Assert(commit_time == replorigin_session_origin_timestamp);
if (IsTransactionState())
{
PGLFlushPosition *flushpos;
multi_insert_finish();
apply_api.on_commit();
/* We need to write end_lsn to the commit record. */
replorigin_session_origin_lsn = end_lsn;
CommitTransactionCommand();
MemoryContextSwitchTo(TopMemoryContext);
/* Track commit lsn */
flushpos = (PGLFlushPosition *) palloc(sizeof(PGLFlushPosition));
flushpos->local_end = XactLastCommitEnd;
flushpos->remote_end = end_lsn;
dlist_push_tail(&lsn_mapping, &flushpos->node);
MemoryContextSwitchTo(MessageContext);
}
/*
* If the xact isn't from the immediate upstream, advance the slot of the
* node it originally came from so we start replay of that node's change
* data at the right place.
*
* This is only necessary when we're streaming data from one peer (A) that
* in turn receives from other peers (B, C), and we plan to later switch to
* replaying directly from B and/or C, no longer receiving forwarded xacts
* from A. When we do the switchover we need to know the right place at
* which to start replay from B and C. We don't actually do that yet, but
* we'll want to be able to do cascaded initialisation in future, so it's
* worth keeping track.
*
* A failure can occur here (see #79) if there's a cascading
* replication configuration like:
*
* X--> Y -> Z
* | ^
* | |
* \---------/
*
* where the direct and indirect connections from X to Z use different
* replication sets so as not to conflict, and where Y and Z are on the
* same PostgreSQL instance. In this case our attempt to advance the
* replication identifier here will ERROR because it's already in use
* for the direct connection from X to Z. So don't do that.
*/
if (remote_origin_id != InvalidRepOriginId &&
remote_origin_id != replorigin_session_origin)
{
elog(DEBUG3, "advancing origin oid %u for forwarded row to %X/%X",
remote_origin_id,
(uint32)(XactLastCommitEnd>>32), (uint32)XactLastCommitEnd);
replorigin_advance(remote_origin_id, remote_origin_lsn,
XactLastCommitEnd, false, false /* XXX ? */);
}
in_remote_transaction = false;
/*
* Stop replay if we're doing limited replay and we've replayed up to the
* last record we're supposed to process.
*/
if (MyApplyWorker->replay_stop_lsn != InvalidXLogRecPtr
&& MyApplyWorker->replay_stop_lsn <= end_lsn)
{
ereport(LOG,
(errmsg("pglogical %s finished processing; replayed to %X/%X of required %X/%X",
MyPGLogicalWorker->worker_type == PGLOGICAL_WORKER_SYNC ? "sync" : "apply",
(uint32)(end_lsn>>32), (uint32)end_lsn,
(uint32)(MyApplyWorker->replay_stop_lsn >>32),
(uint32)MyApplyWorker->replay_stop_lsn)));
/*
* Flush all writes so the latest position can be reported back to the
* sender.
*/
XLogFlush(GetXLogWriteRecPtr());
/*
* Disconnect.
*
* This needs to happen before the pglogical_sync_worker_finish()
* call otherwise slot drop will fail.
*/
PQfinish(applyconn);
/*
* If this is sync worker, finish it.
*/
if (MyPGLogicalWorker->worker_type == PGLOGICAL_WORKER_SYNC)
pglogical_sync_worker_finish();
/* Stop gracefully */
proc_exit(0);
}
process_syncing_tables(end_lsn);
pgstat_report_activity(STATE_IDLE, NULL);
}
/*
* Handle ORIGIN message.
*/
static void
handle_origin(StringInfo s)
{
char *origin;
/*
* ORIGIN message can only come inside remote transaction and before
* any actual writes.
*/
if (!in_remote_transaction || IsTransactionState())
elog(ERROR, "ORIGIN message sent out of order");
/* We have to start transaction here so that we can work with origins. */
ensure_transaction();
origin = pglogical_read_origin(s, &remote_origin_lsn);
remote_origin_id = replorigin_by_name(origin, true);
}
/*
* Handle RELATION message.
*
* Note we don't do validation against local schema here. The validation is
* posponed until first change for given relation comes.
*/
static void
handle_relation(StringInfo s)
{
multi_insert_finish();
(void) pglogical_read_rel(s);
}
static void
handle_insert(StringInfo s)
{
PGLogicalTupleData newtup;
PGLogicalRelation *rel;
bool started_tx = ensure_transaction();
rel = pglogical_read_insert(s, RowExclusiveLock, &newtup);
/* If in list of relations which are being synchronized, skip. */
if (check_syncing_relation(rel->nspname, rel->relname))
{
pglogical_relation_close(rel, NoLock);
return;
}
/* Handle multi_insert capabilities. */
if (use_multi_insert)
{
if (rel != last_insert_rel)
{
multi_insert_finish();
/* Fall through to normal insert. */
}
else
{
apply_api.multi_insert_add_tuple(rel, &newtup);
last_insert_rel_cnt++;
return;
}
}
else if (pglogical_batch_inserts &&
RelationGetRelid(rel->rel) != QueueRelid &&
apply_api.can_multi_insert &&
apply_api.can_multi_insert(rel))
{
if (rel != last_insert_rel)
{
last_insert_rel = rel;
last_insert_rel_cnt = 0;
}
else if (last_insert_rel_cnt++ >= MIN_MULTI_INSERT_TUPLES)
{
use_multi_insert = true;
last_insert_rel_cnt = 0;
}
}
/* Normal insert. */
apply_api.do_insert(rel, &newtup);
/* if INSERT was into our queue, process the message. */
if (RelationGetRelid(rel->rel) == QueueRelid)
{
HeapTuple ht;
LockRelId lockid = rel->rel->rd_lockInfo.lockRelId;
Relation qrel;
multi_insert_finish();
MemoryContextSwitchTo(MessageContext);
ht = heap_form_tuple(RelationGetDescr(rel->rel),
newtup.values, newtup.nulls);
LockRelationIdForSession(&lockid, RowExclusiveLock);
pglogical_relation_close(rel, NoLock);
apply_api.on_commit();
handle_queued_message(ht, started_tx);
heap_freetuple(ht);
qrel = heap_open(QueueRelid, RowExclusiveLock);
UnlockRelationIdForSession(&lockid, RowExclusiveLock);
heap_close(qrel, NoLock);
apply_api.on_begin();
MemoryContextSwitchTo(MessageContext);
// if (oldxid != GetTopTransactionId())
// CommitTransactionCommand();
}
else
pglogical_relation_close(rel, NoLock);
}
static void
multi_insert_finish(void)
{
if (use_multi_insert && last_insert_rel_cnt)
{
apply_api.multi_insert_finish(last_insert_rel);
pglogical_relation_close(last_insert_rel, NoLock);
use_multi_insert = false;
last_insert_rel = NULL;
last_insert_rel_cnt = 0;
}
}
static void
handle_update(StringInfo s)
{
PGLogicalTupleData oldtup;
PGLogicalTupleData newtup;
PGLogicalRelation *rel;
bool hasoldtup;
ensure_transaction();
multi_insert_finish();
rel = pglogical_read_update(s, RowExclusiveLock, &hasoldtup, &oldtup,
&newtup);
/* If in list of relations which are being synchronized, skip. */
if (check_syncing_relation(rel->nspname, rel->relname))
{
pglogical_relation_close(rel, NoLock);
return;
}
apply_api.do_update(rel, hasoldtup ? &oldtup : &newtup, &newtup);
pglogical_relation_close(rel, NoLock);
}
static void
handle_delete(StringInfo s)
{
PGLogicalTupleData oldtup;
PGLogicalRelation *rel;
ensure_transaction();
multi_insert_finish();
rel = pglogical_read_delete(s, RowExclusiveLock, &oldtup);
/* If in list of relations which are being synchronized, skip. */
if (check_syncing_relation(rel->nspname, rel->relname))
{
pglogical_relation_close(rel, NoLock);
return;
}
apply_api.do_delete(rel, &oldtup);
pglogical_relation_close(rel, NoLock);
}
inline static bool
getmsgisend(StringInfo msg)
{
return msg->cursor == msg->len;
}
static void
handle_startup(StringInfo s)
{
uint8 msgver = pq_getmsgbyte(s);
if (msgver != 1)
elog(ERROR, "Expected startup message version 1, but got %u", msgver);
/*
* The startup message consists of null-terminated strings as key/value
* pairs. The first entry is always the format identifier.
*/
do {
const char *k, *v;
k = pq_getmsgstring(s);
if (strlen(k) == 0)
ereport(ERROR,
(errcode(ERRCODE_PROTOCOL_VIOLATION),
errmsg("invalid startup message: key has zero length")));
if (getmsgisend(s))
ereport(ERROR,
(errcode(ERRCODE_PROTOCOL_VIOLATION),
errmsg("invalid startup message: key '%s' has no following value", k)));
/* It's OK to have a zero length value */
v = pq_getmsgstring(s);
handle_startup_param(k, v);
} while (!getmsgisend(s));
}
static bool
parse_bool_param(const char *key, const char *value)
{
bool result;
if (!parse_bool(value, &result))
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("couldn't parse value '%s' for key '%s' as boolean",
value, key)));
return result;
}
static void
handle_startup_param(const char *key, const char *value)
{
elog(DEBUG2, "apply got pglogical startup msg param %s=%s", key, value);
if (strcmp(key, "pg_version") == 0)
elog(DEBUG1, "upstream Pg version is %s", value);
if (strcmp(key, "encoding") == 0)
{
int encoding = pg_char_to_encoding(value);
if (encoding != GetDatabaseEncoding())
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("expected encoding=%s from upstream but got %s",
GetDatabaseEncodingName(), value)));
}
if (strcmp(key, "forward_changeset_origins") == 0)
{
bool fwd = parse_bool_param(key, value);
/* FIXME: Store this somewhere */
elog(DEBUG1, "changeset origin forwarding enabled: %s", fwd ? "t" : "f");
}
/*
* We just ignore a bunch of parameters here because we specify what we
* require when we send our params to the upstream. It's required to ERROR
* if it can't match what we asked for. It may send the startup message
* first, but it'll be followed by an ERROR if it does. There's no need
* to check params we can't do anything about mismatches of, like protocol
* versions and type sizes.
*/
}
static RangeVar *
parse_relation_message(Jsonb *message)
{
JsonbIterator *it;
JsonbValue v;
int r;
int level = 0;
char *key = NULL;
char **parse_res = NULL;
char *nspname = NULL;
char *relname = NULL;
/* Parse and validate the json message. */
if (!JB_ROOT_IS_OBJECT(message))
elog(ERROR, "malformed message in queued message tuple: root is not object");
it = JsonbIteratorInit(&message->root);
while ((r = JsonbIteratorNext(&it, &v, false)) != WJB_DONE)
{
if (level == 0 && r != WJB_BEGIN_OBJECT)
elog(ERROR, "root element needs to be an object");
else if (level == 0 && r == WJB_BEGIN_OBJECT)
{
level++;
}
else if (level == 1 && r == WJB_KEY)
{
if (strncmp(v.val.string.val, "schema_name", v.val.string.len) == 0)
parse_res = &nspname;
else if (strncmp(v.val.string.val, "table_name", v.val.string.len) == 0)
parse_res = &relname;
else
elog(ERROR, "unexpected key: %s",
pnstrdup(v.val.string.val, v.val.string.len));
key = v.val.string.val;
}
else if (level == 1 && r == WJB_VALUE)
{
if (!key)
elog(ERROR, "in wrong state when parsing key");
if (v.type != jbvString)
elog(ERROR, "unexpected type for key '%s': %u", key, v.type);
*parse_res = pnstrdup(v.val.string.val, v.val.string.len);
}
else if (level == 1 && r != WJB_END_OBJECT)
{
elog(ERROR, "unexpected content: %u at level %d", r, level);
}
else if (r == WJB_END_OBJECT)
{
level--;
parse_res = NULL;
key = NULL;
}
else
elog(ERROR, "unexpected content: %u at level %d", r, level);
}
/* Check if we got both schema and table names. */
if (!nspname)
elog(ERROR, "missing schema_name in relation message");
if (!relname)
elog(ERROR, "missing table_name in relation message");
return makeRangeVar(nspname, relname, -1);
}
/*
* Handle TRUNCATE message comming via queue table.
*/
static void
handle_truncate(QueuedMessage *queued_message)
{
RangeVar *rv;
/*
* If table doesn't exist locally, it can't be subscribed.
*
* TODO: should we error here?
*/
rv = parse_relation_message(queued_message->message);
/* If in list of relations which are being synchronized, skip. */
if (check_syncing_relation(rv->schemaname, rv->relname))
return;
truncate_table(rv->schemaname, rv->relname);
}
/*
* Handle TABLESYNC message comming via queue table.
*/
static void
handle_table_sync(QueuedMessage *queued_message)
{
RangeVar *rv;
MemoryContext oldcontext;
PGLogicalSyncStatus *oldsync;
PGLogicalSyncStatus newsync;
rv = parse_relation_message(queued_message->message);
oldsync = get_table_sync_status(MyApplyWorker->subid, rv->schemaname,
rv->relname, true);
if (oldsync)
{
elog(INFO,
"table sync came from queue for table %s.%s which already being synchronized, skipping",
rv->schemaname, rv->relname);
return;
}
/*
* Create synchronization status for the subscription.
* Currently we only support data sync for tables.
*/
newsync.kind = SYNC_KIND_DATA;
newsync.subid = MyApplyWorker->subid;
newsync.nspname = rv->schemaname;
newsync.relname = rv->relname;
newsync.status = SYNC_STATUS_INIT;
create_local_sync_status(&newsync);
/* Keep the lists persistent. */
oldcontext = MemoryContextSwitchTo(TopMemoryContext);
SyncingTables = lappend(SyncingTables,
makeRangeVar(pstrdup(rv->schemaname),
pstrdup(rv->relname), -1));
MemoryContextSwitchTo(oldcontext);
}
/*
* Handle SEQUENCE message comming via queue table.
*/
static void
handle_sequence(QueuedMessage *queued_message)
{
Jsonb *message = queued_message->message;
JsonbIterator *it;
JsonbValue v;
int r;
int level = 0;
char *key = NULL;
char **parse_res = NULL;
char *nspname = NULL;
char *relname = NULL;
char *last_value_raw = NULL;
int64 last_value;
Oid nspoid;
Oid reloid;
/* Parse and validate the json message. */
if (!JB_ROOT_IS_OBJECT(message))
elog(ERROR, "malformed message in queued message tuple: root is not object");
it = JsonbIteratorInit(&message->root);
while ((r = JsonbIteratorNext(&it, &v, false)) != WJB_DONE)
{
if (level == 0 && r != WJB_BEGIN_OBJECT)
elog(ERROR, "root element needs to be an object");
else if (level == 0 && r == WJB_BEGIN_OBJECT)
{
level++;
}
else if (level == 1 && r == WJB_KEY)
{
if (strncmp(v.val.string.val, "schema_name", v.val.string.len) == 0)
parse_res = &nspname;
else if (strncmp(v.val.string.val, "sequence_name", v.val.string.len) == 0)
parse_res = &relname;
else if (strncmp(v.val.string.val, "last_value", v.val.string.len) == 0)
parse_res = &last_value_raw;
else
elog(ERROR, "unexpected key: %s",
pnstrdup(v.val.string.val, v.val.string.len));
key = v.val.string.val;
}
else if (level == 1 && r == WJB_VALUE)
{
if (!key)
elog(ERROR, "in wrong state when parsing key");
if (v.type != jbvString)
elog(ERROR, "unexpected type for key '%s': %u", key, v.type);
*parse_res = pnstrdup(v.val.string.val, v.val.string.len);
}
else if (level == 1 && r != WJB_END_OBJECT)
{
elog(ERROR, "unexpected content: %u at level %d", r, level);
}
else if (r == WJB_END_OBJECT)
{
level--;
parse_res = NULL;
key = NULL;
}
else
elog(ERROR, "unexpected content: %u at level %d", r, level);
}
/* Check if we got both schema and table names. */
if (!nspname)
elog(ERROR, "missing schema_name in sequence message");
if (!relname)
elog(ERROR, "missing table_name in sequence message");
if (!last_value_raw)
elog(ERROR, "missing last_value in sequence message");
nspoid = get_namespace_oid(nspname, false);
reloid = get_relname_relid(relname, nspoid);
scanint8(last_value_raw, false, &last_value);
DirectFunctionCall2(setval_oid, ObjectIdGetDatum(reloid),
Int64GetDatum(last_value));
}
/*
* Handle SQL message comming via queue table.
*/
static void
handle_sql(QueuedMessage *queued_message, bool tx_just_started)
{
JsonbIterator *it;
JsonbValue v;
int r;
char *sql;
/* Validate the json and extract the SQL string from it. */
if (!JB_ROOT_IS_SCALAR(queued_message->message))
elog(ERROR, "malformed message in queued message tuple: root is not scalar");
it = JsonbIteratorInit(&queued_message->message->root);
r = JsonbIteratorNext(&it, &v, false);
if (r != WJB_BEGIN_ARRAY)
elog(ERROR, "malformed message in queued message tuple, item type %d expected %d", r, WJB_BEGIN_ARRAY);
r = JsonbIteratorNext(&it, &v, false);
if (r != WJB_ELEM)
elog(ERROR, "malformed message in queued message tuple, item type %d expected %d", r, WJB_ELEM);
if (v.type != jbvString)
elog(ERROR, "malformed message in queued message tuple, expected value type %d got %d", jbvString, v.type);
sql = pnstrdup(v.val.string.val, v.val.string.len);
r = JsonbIteratorNext(&it, &v, false);
if (r != WJB_END_ARRAY)
elog(ERROR, "malformed message in queued message tuple, item type %d expected %d", r, WJB_END_ARRAY);
r = JsonbIteratorNext(&it, &v, false);
if (r != WJB_DONE)
elog(ERROR, "malformed message in queued message tuple, item type %d expected %d", r, WJB_DONE);
/* Run the extracted SQL. */
pglogical_execute_sql_command(sql, queued_message->role, tx_just_started);
}
/*
* Handles messages comming from the queue.
*/
static void
handle_queued_message(HeapTuple msgtup, bool tx_just_started)
{
QueuedMessage *queued_message = queued_message_from_tuple(msgtup);
switch (queued_message->message_type)
{
case QUEUE_COMMAND_TYPE_SQL:
handle_sql(queued_message, tx_just_started);
break;
case QUEUE_COMMAND_TYPE_TRUNCATE:
handle_truncate(queued_message);
break;
case QUEUE_COMMAND_TYPE_TABLESYNC:
handle_table_sync(queued_message);
break;
case QUEUE_COMMAND_TYPE_SEQUENCE:
handle_sequence(queued_message);
break;
default:
elog(ERROR, "unknown message type '%c'",
queued_message->message_type);
}
}
static void
replication_handler(StringInfo s)
{
char action = pq_getmsgbyte(s);
switch (action)
{
/* BEGIN */
case 'B':
handle_begin(s);
break;
/* COMMIT */
case 'C':
handle_commit(s);
break;
/* ORIGIN */
case 'O':
handle_origin(s);
break;
/* RELATION */
case 'R':
handle_relation(s);
break;
/* INSERT */
case 'I':
handle_insert(s);
break;
/* UPDATE */
case 'U':
handle_update(s);
break;
/* DELETE */
case 'D':
handle_delete(s);
break;
/* STARTUP MESSAGE */
case 'S':
handle_startup(s);
break;
default:
elog(ERROR, "unknown action of type %c", action);
}
}
/*
* Figure out which write/flush positions to report to the walsender process.
*
* We can't simply report back the last LSN the walsender sent us because the
* local transaction might not yet be flushed to disk locally. Instead we
* build a list that associates local with remote LSNs for every commit. When
* reporting back the flush position to the sender we iterate that list and
* check which entries on it are already locally flushed. Those we can report
* as having been flushed.
*
* Returns true if there's no outstanding transactions that need to be
* flushed.
*/
static bool
get_flush_position(XLogRecPtr *write, XLogRecPtr *flush)
{
dlist_mutable_iter iter;
XLogRecPtr local_flush = GetFlushRecPtr();
*write = InvalidXLogRecPtr;
*flush = InvalidXLogRecPtr;
dlist_foreach_modify(iter, &lsn_mapping)
{
PGLFlushPosition *pos =
dlist_container(PGLFlushPosition, node, iter.cur);
*write = pos->remote_end;
if (pos->local_end <= local_flush)
{
*flush = pos->remote_end;
dlist_delete(iter.cur);
pfree(pos);
}
else
{
/*
* Don't want to uselessly iterate over the rest of the list which
* could potentially be long. Instead get the last element and
* grab the write position from there.
*/
pos = dlist_tail_element(PGLFlushPosition, node,
&lsn_mapping);
*write = pos->remote_end;
return false;