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/*-------------------------------------------------------------------------
*
* pgoutput.c
* Logical Replication output plugin
*
* Copyright (c) 2012-2020, PostgreSQL Global Development Group
*
* IDENTIFICATION
* src/backend/replication/pgoutput/pgoutput.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "catalog/pg_publication.h"
#include "fmgr.h"
#include "replication/logical.h"
#include "replication/logicalproto.h"
#include "replication/origin.h"
#include "replication/pgoutput.h"
#include "utils/int8.h"
#include "utils/inval.h"
#include "utils/memutils.h"
#include "utils/syscache.h"
#include "utils/varlena.h"
PG_MODULE_MAGIC;
extern void _PG_output_plugin_init(OutputPluginCallbacks *cb);
static void pgoutput_startup(LogicalDecodingContext *ctx,
OutputPluginOptions *opt, bool is_init);
static void pgoutput_shutdown(LogicalDecodingContext *ctx);
static void pgoutput_begin_txn(LogicalDecodingContext *ctx,
ReorderBufferTXN *txn);
static void pgoutput_commit_txn(LogicalDecodingContext *ctx,
ReorderBufferTXN *txn, XLogRecPtr commit_lsn);
static void pgoutput_change(LogicalDecodingContext *ctx,
ReorderBufferTXN *txn, Relation rel,
ReorderBufferChange *change);
static void pgoutput_truncate(LogicalDecodingContext *ctx,
ReorderBufferTXN *txn, int nrelations, Relation relations[],
ReorderBufferChange *change);
static bool pgoutput_origin_filter(LogicalDecodingContext *ctx,
RepOriginId origin_id);
static bool publications_valid;
static List *LoadPublications(List *pubnames);
static void publication_invalidation_cb(Datum arg, int cacheid,
uint32 hashvalue);
/* Entry in the map used to remember which relation schemas we sent. */
typedef struct RelationSyncEntry
{
Oid relid; /* relation oid */
bool schema_sent; /* did we send the schema? */
bool replicate_valid;
PublicationActions pubactions;
} RelationSyncEntry;
/* Map used to remember which relation schemas we sent. */
static HTAB *RelationSyncCache = NULL;
static void init_rel_sync_cache(MemoryContext decoding_context);
static RelationSyncEntry *get_rel_sync_entry(PGOutputData *data, Oid relid);
static void rel_sync_cache_relation_cb(Datum arg, Oid relid);
static void rel_sync_cache_publication_cb(Datum arg, int cacheid,
uint32 hashvalue);
/*
* Specify output plugin callbacks
*/
void
_PG_output_plugin_init(OutputPluginCallbacks *cb)
{
AssertVariableIsOfType(&_PG_output_plugin_init, LogicalOutputPluginInit);
cb->startup_cb = pgoutput_startup;
cb->begin_cb = pgoutput_begin_txn;
cb->change_cb = pgoutput_change;
cb->truncate_cb = pgoutput_truncate;
cb->commit_cb = pgoutput_commit_txn;
cb->filter_by_origin_cb = pgoutput_origin_filter;
cb->shutdown_cb = pgoutput_shutdown;
}
static void
parse_output_parameters(List *options, uint32 *protocol_version,
List **publication_names)
{
ListCell *lc;
bool protocol_version_given = false;
bool publication_names_given = false;
foreach(lc, options)
{
DefElem *defel = (DefElem *) lfirst(lc);
Assert(defel->arg == NULL || IsA(defel->arg, String));
/* Check each param, whether or not we recognize it */
if (strcmp(defel->defname, "proto_version") == 0)
{
int64 parsed;
if (protocol_version_given)
ereport(ERROR,
(errcode(ERRCODE_SYNTAX_ERROR),
errmsg("conflicting or redundant options")));
protocol_version_given = true;
if (!scanint8(strVal(defel->arg), true, &parsed))
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("invalid proto_version")));
if (parsed > PG_UINT32_MAX || parsed < 0)
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("proto_version \"%s\" out of range",
strVal(defel->arg))));
*protocol_version = (uint32) parsed;
}
else if (strcmp(defel->defname, "publication_names") == 0)
{
if (publication_names_given)
ereport(ERROR,
(errcode(ERRCODE_SYNTAX_ERROR),
errmsg("conflicting or redundant options")));
publication_names_given = true;
if (!SplitIdentifierString(strVal(defel->arg), ',',
publication_names))
ereport(ERROR,
(errcode(ERRCODE_INVALID_NAME),
errmsg("invalid publication_names syntax")));
}
else
elog(ERROR, "unrecognized pgoutput option: %s", defel->defname);
}
}
/*
* Initialize this plugin
*/
static void
pgoutput_startup(LogicalDecodingContext *ctx, OutputPluginOptions *opt,
bool is_init)
{
PGOutputData *data = palloc0(sizeof(PGOutputData));
/* Create our memory context for private allocations. */
data->context = AllocSetContextCreate(ctx->context,
"logical replication output context",
ALLOCSET_DEFAULT_SIZES);
ctx->output_plugin_private = data;
/* This plugin uses binary protocol. */
opt->output_type = OUTPUT_PLUGIN_BINARY_OUTPUT;
/*
* This is replication start and not slot initialization.
*
* Parse and validate options passed by the client.
*/
if (!is_init)
{
/* Parse the params and ERROR if we see any we don't recognize */
parse_output_parameters(ctx->output_plugin_options,
&data->protocol_version,
&data->publication_names);
/* Check if we support requested protocol */
if (data->protocol_version > LOGICALREP_PROTO_VERSION_NUM)
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("client sent proto_version=%d but we only support protocol %d or lower",
data->protocol_version, LOGICALREP_PROTO_VERSION_NUM)));
if (data->protocol_version < LOGICALREP_PROTO_MIN_VERSION_NUM)
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("client sent proto_version=%d but we only support protocol %d or higher",
data->protocol_version, LOGICALREP_PROTO_MIN_VERSION_NUM)));
if (list_length(data->publication_names) < 1)
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("publication_names parameter missing")));
/* Init publication state. */
data->publications = NIL;
publications_valid = false;
CacheRegisterSyscacheCallback(PUBLICATIONOID,
publication_invalidation_cb,
(Datum) 0);
/* Initialize relation schema cache. */
init_rel_sync_cache(CacheMemoryContext);
}
}
/*
* BEGIN callback
*/
static void
pgoutput_begin_txn(LogicalDecodingContext *ctx, ReorderBufferTXN *txn)
{
bool send_replication_origin = txn->origin_id != InvalidRepOriginId;
OutputPluginPrepareWrite(ctx, !send_replication_origin);
logicalrep_write_begin(ctx->out, txn);
if (send_replication_origin)
{
char *origin;
/* Message boundary */
OutputPluginWrite(ctx, false);
OutputPluginPrepareWrite(ctx, true);
/*----------
* XXX: which behaviour do we want here?
*
* Alternatives:
* - don't send origin message if origin name not found
* (that's what we do now)
* - throw error - that will break replication, not good
* - send some special "unknown" origin
*----------
*/
if (replorigin_by_oid(txn->origin_id, true, &origin))
logicalrep_write_origin(ctx->out, origin, txn->origin_lsn);
}
OutputPluginWrite(ctx, true);
}
/*
* COMMIT callback
*/
static void
pgoutput_commit_txn(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
XLogRecPtr commit_lsn)
{
OutputPluginUpdateProgress(ctx);
OutputPluginPrepareWrite(ctx, true);
logicalrep_write_commit(ctx->out, txn, commit_lsn);
OutputPluginWrite(ctx, true);
}
/*
* Write the relation schema if the current schema hasn't been sent yet.
*/
static void
maybe_send_schema(LogicalDecodingContext *ctx,
Relation relation, RelationSyncEntry *relentry)
{
if (!relentry->schema_sent)
{
TupleDesc desc;
int i;
desc = RelationGetDescr(relation);
/*
* Write out type info if needed. We do that only for user-created
* types. We use FirstGenbkiObjectId as the cutoff, so that we only
* consider objects with hand-assigned OIDs to be "built in", not for
* instance any function or type defined in the information_schema.
* This is important because only hand-assigned OIDs can be expected
* to remain stable across major versions.
*/
for (i = 0; i < desc->natts; i++)
{
Form_pg_attribute att = TupleDescAttr(desc, i);
if (att->attisdropped || att->attgenerated)
continue;
if (att->atttypid < FirstGenbkiObjectId)
continue;
OutputPluginPrepareWrite(ctx, false);
logicalrep_write_typ(ctx->out, att->atttypid);
OutputPluginWrite(ctx, false);
}
OutputPluginPrepareWrite(ctx, false);
logicalrep_write_rel(ctx->out, relation);
OutputPluginWrite(ctx, false);
relentry->schema_sent = true;
}
}
/*
* Sends the decoded DML over wire.
*/
static void
pgoutput_change(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
Relation relation, ReorderBufferChange *change)
{
PGOutputData *data = (PGOutputData *) ctx->output_plugin_private;
MemoryContext old;
RelationSyncEntry *relentry;
if (!is_publishable_relation(relation))
return;
relentry = get_rel_sync_entry(data, RelationGetRelid(relation));
/* First check the table filter */
switch (change->action)
{
case REORDER_BUFFER_CHANGE_INSERT:
if (!relentry->pubactions.pubinsert)
return;
break;
case REORDER_BUFFER_CHANGE_UPDATE:
if (!relentry->pubactions.pubupdate)
return;
break;
case REORDER_BUFFER_CHANGE_DELETE:
if (!relentry->pubactions.pubdelete)
return;
break;
default:
Assert(false);
}
/* Avoid leaking memory by using and resetting our own context */
old = MemoryContextSwitchTo(data->context);
maybe_send_schema(ctx, relation, relentry);
/* Send the data */
switch (change->action)
{
case REORDER_BUFFER_CHANGE_INSERT:
OutputPluginPrepareWrite(ctx, true);
logicalrep_write_insert(ctx->out, relation,
&change->data.tp.newtuple->tuple);
OutputPluginWrite(ctx, true);
break;
case REORDER_BUFFER_CHANGE_UPDATE:
{
HeapTuple oldtuple = change->data.tp.oldtuple ?
&change->data.tp.oldtuple->tuple : NULL;
OutputPluginPrepareWrite(ctx, true);
logicalrep_write_update(ctx->out, relation, oldtuple,
&change->data.tp.newtuple->tuple);
OutputPluginWrite(ctx, true);
break;
}
case REORDER_BUFFER_CHANGE_DELETE:
if (change->data.tp.oldtuple)
{
OutputPluginPrepareWrite(ctx, true);
logicalrep_write_delete(ctx->out, relation,
&change->data.tp.oldtuple->tuple);
OutputPluginWrite(ctx, true);
}
else
elog(DEBUG1, "didn't send DELETE change because of missing oldtuple");
break;
default:
Assert(false);
}
/* Cleanup */
MemoryContextSwitchTo(old);
MemoryContextReset(data->context);
}
static void
pgoutput_truncate(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
int nrelations, Relation relations[], ReorderBufferChange *change)
{
PGOutputData *data = (PGOutputData *) ctx->output_plugin_private;
MemoryContext old;
RelationSyncEntry *relentry;
int i;
int nrelids;
Oid *relids;
old = MemoryContextSwitchTo(data->context);
relids = palloc0(nrelations * sizeof(Oid));
nrelids = 0;
for (i = 0; i < nrelations; i++)
{
Relation relation = relations[i];
Oid relid = RelationGetRelid(relation);
if (!is_publishable_relation(relation))
continue;
relentry = get_rel_sync_entry(data, relid);
if (!relentry->pubactions.pubtruncate)
continue;
relids[nrelids++] = relid;
maybe_send_schema(ctx, relation, relentry);
}
if (nrelids > 0)
{
OutputPluginPrepareWrite(ctx, true);
logicalrep_write_truncate(ctx->out,
nrelids,
relids,
change->data.truncate.cascade,
change->data.truncate.restart_seqs);
OutputPluginWrite(ctx, true);
}
MemoryContextSwitchTo(old);
MemoryContextReset(data->context);
}
/*
* Currently we always forward.
*/
static bool
pgoutput_origin_filter(LogicalDecodingContext *ctx,
RepOriginId origin_id)
{
return false;
}
/*
* Shutdown the output plugin.
*
* Note, we don't need to clean the data->context as it's child context
* of the ctx->context so it will be cleaned up by logical decoding machinery.
*/
static void
pgoutput_shutdown(LogicalDecodingContext *ctx)
{
if (RelationSyncCache)
{
hash_destroy(RelationSyncCache);
RelationSyncCache = NULL;
}
}
/*
* Load publications from the list of publication names.
*/
static List *
LoadPublications(List *pubnames)
{
List *result = NIL;
ListCell *lc;
foreach(lc, pubnames)
{
char *pubname = (char *) lfirst(lc);
Publication *pub = GetPublicationByName(pubname, false);
result = lappend(result, pub);
}
return result;
}
/*
* Publication cache invalidation callback.
*/
static void
publication_invalidation_cb(Datum arg, int cacheid, uint32 hashvalue)
{
publications_valid = false;
/*
* Also invalidate per-relation cache so that next time the filtering info
* is checked it will be updated with the new publication settings.
*/
rel_sync_cache_publication_cb(arg, cacheid, hashvalue);
}
/*
* Initialize the relation schema sync cache for a decoding session.
*
* The hash table is destroyed at the end of a decoding session. While
* relcache invalidations still exist and will still be invoked, they
* will just see the null hash table global and take no action.
*/
static void
init_rel_sync_cache(MemoryContext cachectx)
{
HASHCTL ctl;
MemoryContext old_ctxt;
if (RelationSyncCache != NULL)
return;
/* Make a new hash table for the cache */
MemSet(&ctl, 0, sizeof(ctl));
ctl.keysize = sizeof(Oid);
ctl.entrysize = sizeof(RelationSyncEntry);
ctl.hcxt = cachectx;
old_ctxt = MemoryContextSwitchTo(cachectx);
RelationSyncCache = hash_create("logical replication output relation cache",
128, &ctl,
HASH_ELEM | HASH_CONTEXT | HASH_BLOBS);
(void) MemoryContextSwitchTo(old_ctxt);
Assert(RelationSyncCache != NULL);
CacheRegisterRelcacheCallback(rel_sync_cache_relation_cb, (Datum) 0);
CacheRegisterSyscacheCallback(PUBLICATIONRELMAP,
rel_sync_cache_publication_cb,
(Datum) 0);
}
/*
* Find or create entry in the relation schema cache.
*/
static RelationSyncEntry *
get_rel_sync_entry(PGOutputData *data, Oid relid)
{
RelationSyncEntry *entry;
bool found;
MemoryContext oldctx;
Assert(RelationSyncCache != NULL);
/* Find cached function info, creating if not found */
oldctx = MemoryContextSwitchTo(CacheMemoryContext);
entry = (RelationSyncEntry *) hash_search(RelationSyncCache,
(void *) &relid,
HASH_ENTER, &found);
MemoryContextSwitchTo(oldctx);
Assert(entry != NULL);
/* Not found means schema wasn't sent */
if (!found || !entry->replicate_valid)
{
List *pubids = GetRelationPublications(relid);
ListCell *lc;
/* Reload publications if needed before use. */
if (!publications_valid)
{
oldctx = MemoryContextSwitchTo(CacheMemoryContext);
if (data->publications)
list_free_deep(data->publications);
data->publications = LoadPublications(data->publication_names);
MemoryContextSwitchTo(oldctx);
publications_valid = true;
}
/*
* Build publication cache. We can't use one provided by relcache as
* relcache considers all publications given relation is in, but here
* we only need to consider ones that the subscriber requested.
*/
entry->pubactions.pubinsert = entry->pubactions.pubupdate =
entry->pubactions.pubdelete = entry->pubactions.pubtruncate = false;
foreach(lc, data->publications)
{
Publication *pub = lfirst(lc);
if (pub->alltables || list_member_oid(pubids, pub->oid))
{
entry->pubactions.pubinsert |= pub->pubactions.pubinsert;
entry->pubactions.pubupdate |= pub->pubactions.pubupdate;
entry->pubactions.pubdelete |= pub->pubactions.pubdelete;
entry->pubactions.pubtruncate |= pub->pubactions.pubtruncate;
}
if (entry->pubactions.pubinsert && entry->pubactions.pubupdate &&
entry->pubactions.pubdelete && entry->pubactions.pubtruncate)
break;
}
list_free(pubids);
entry->replicate_valid = true;
}
if (!found)
entry->schema_sent = false;
return entry;
}
/*
* Relcache invalidation callback
*/
static void
rel_sync_cache_relation_cb(Datum arg, Oid relid)
{
RelationSyncEntry *entry;
/*
* We can get here if the plugin was used in SQL interface as the
* RelSchemaSyncCache is destroyed when the decoding finishes, but there
* is no way to unregister the relcache invalidation callback.
*/
if (RelationSyncCache == NULL)
return;
/*
* Nobody keeps pointers to entries in this hash table around outside
* logical decoding callback calls - but invalidation events can come in
* *during* a callback if we access the relcache in the callback. Because
* of that we must mark the cache entry as invalid but not remove it from
* the hash while it could still be referenced, then prune it at a later
* safe point.
*
* Getting invalidations for relations that aren't in the table is
* entirely normal, since there's no way to unregister for an invalidation
* event. So we don't care if it's found or not.
*/
entry = (RelationSyncEntry *) hash_search(RelationSyncCache, &relid,
HASH_FIND, NULL);
/*
* Reset schema sent status as the relation definition may have changed.
*/
if (entry != NULL)
entry->schema_sent = false;
}
/*
* Publication relation map syscache invalidation callback
*/
static void
rel_sync_cache_publication_cb(Datum arg, int cacheid, uint32 hashvalue)
{
HASH_SEQ_STATUS status;
RelationSyncEntry *entry;
/*
* We can get here if the plugin was used in SQL interface as the
* RelSchemaSyncCache is destroyed when the decoding finishes, but there
* is no way to unregister the relcache invalidation callback.
*/
if (RelationSyncCache == NULL)
return;
/*
* There is no way to find which entry in our cache the hash belongs to so
* mark the whole cache as invalid.
*/
hash_seq_init(&status, RelationSyncCache);
while ((entry = (RelationSyncEntry *) hash_seq_search(&status)) != NULL)
entry->replicate_valid = false;
}
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