Adding upstream version 16.2.upstream/16.2

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 377 insertions, 0 deletions

diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
new file mode 100644
index 0000000..55a24c0
--- /dev/null
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -0,0 +1,377 @@
+/*-------------------------------------------------------------------------
+ *
+ * logicalfuncs.c
+ *
+ *	   Support functions for using logical decoding and management of
+ *	   logical replication slots via SQL.
+ *
+ *
+ * Copyright (c) 2012-2023, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  src/backend/replication/logical/logicalfuncs.c
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include <unistd.h>
+
+#include "access/xact.h"
+#include "access/xlog_internal.h"
+#include "access/xlogrecovery.h"
+#include "access/xlogutils.h"
+#include "catalog/pg_type.h"
+#include "fmgr.h"
+#include "funcapi.h"
+#include "mb/pg_wchar.h"
+#include "miscadmin.h"
+#include "nodes/makefuncs.h"
+#include "replication/decode.h"
+#include "replication/logical.h"
+#include "replication/message.h"
+#include "storage/fd.h"
+#include "utils/array.h"
+#include "utils/builtins.h"
+#include "utils/inval.h"
+#include "utils/lsyscache.h"
+#include "utils/memutils.h"
+#include "utils/pg_lsn.h"
+#include "utils/regproc.h"
+#include "utils/resowner.h"
+
+/* Private data for writing out data */
+typedef struct DecodingOutputState
+{
+	Tuplestorestate *tupstore;
+	TupleDesc	tupdesc;
+	bool		binary_output;
+	int64		returned_rows;
+} DecodingOutputState;
+
+/*
+ * Prepare for an output plugin write.
+ */
+static void
+LogicalOutputPrepareWrite(LogicalDecodingContext *ctx, XLogRecPtr lsn, TransactionId xid,
+						  bool last_write)
+{
+	resetStringInfo(ctx->out);
+}
+
+/*
+ * Perform output plugin write into tuplestore.
+ */
+static void
+LogicalOutputWrite(LogicalDecodingContext *ctx, XLogRecPtr lsn, TransactionId xid,
+				   bool last_write)
+{
+	Datum		values[3];
+	bool		nulls[3];
+	DecodingOutputState *p;
+
+	/* SQL Datums can only be of a limited length... */
+	if (ctx->out->len > MaxAllocSize - VARHDRSZ)
+		elog(ERROR, "too much output for sql interface");
+
+	p = (DecodingOutputState *) ctx->output_writer_private;
+
+	memset(nulls, 0, sizeof(nulls));
+	values[0] = LSNGetDatum(lsn);
+	values[1] = TransactionIdGetDatum(xid);
+
+	/*
+	 * Assert ctx->out is in database encoding when we're writing textual
+	 * output.
+	 */
+	if (!p->binary_output)
+		Assert(pg_verify_mbstr(GetDatabaseEncoding(),
+							   ctx->out->data, ctx->out->len,
+							   false));
+
+	/* ick, but cstring_to_text_with_len works for bytea perfectly fine */
+	values[2] = PointerGetDatum(cstring_to_text_with_len(ctx->out->data, ctx->out->len));
+
+	tuplestore_putvalues(p->tupstore, p->tupdesc, values, nulls);
+	p->returned_rows++;
+}
+
+/*
+ * Helper function for the various SQL callable logical decoding functions.
+ */
+static Datum
+pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool binary)
+{
+	Name		name;
+	XLogRecPtr	upto_lsn;
+	int32		upto_nchanges;
+	ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+	MemoryContext per_query_ctx;
+	MemoryContext oldcontext;
+	XLogRecPtr	end_of_wal;
+	LogicalDecodingContext *ctx;
+	ResourceOwner old_resowner = CurrentResourceOwner;
+	ArrayType  *arr;
+	Size		ndim;
+	List	   *options = NIL;
+	DecodingOutputState *p;
+
+	CheckSlotPermissions();
+
+	CheckLogicalDecodingRequirements();
+
+	if (PG_ARGISNULL(0))
+		ereport(ERROR,
+				(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
+				 errmsg("slot name must not be null")));
+	name = PG_GETARG_NAME(0);
+
+	if (PG_ARGISNULL(1))
+		upto_lsn = InvalidXLogRecPtr;
+	else
+		upto_lsn = PG_GETARG_LSN(1);
+
+	if (PG_ARGISNULL(2))
+		upto_nchanges = InvalidXLogRecPtr;
+	else
+		upto_nchanges = PG_GETARG_INT32(2);
+
+	if (PG_ARGISNULL(3))
+		ereport(ERROR,
+				(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
+				 errmsg("options array must not be null")));
+	arr = PG_GETARG_ARRAYTYPE_P(3);
+
+	/* state to write output to */
+	p = palloc0(sizeof(DecodingOutputState));
+
+	p->binary_output = binary;
+
+	per_query_ctx = rsinfo->econtext->ecxt_per_query_memory;
+	oldcontext = MemoryContextSwitchTo(per_query_ctx);
+
+	/* Deconstruct options array */
+	ndim = ARR_NDIM(arr);
+	if (ndim > 1)
+	{
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("array must be one-dimensional")));
+	}
+	else if (array_contains_nulls(arr))
+	{
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("array must not contain nulls")));
+	}
+	else if (ndim == 1)
+	{
+		int			nelems;
+		Datum	   *datum_opts;
+		int			i;
+
+		Assert(ARR_ELEMTYPE(arr) == TEXTOID);
+
+		deconstruct_array_builtin(arr, TEXTOID, &datum_opts, NULL, &nelems);
+
+		if (nelems % 2 != 0)
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					 errmsg("array must have even number of elements")));
+
+		for (i = 0; i < nelems; i += 2)
+		{
+			char	   *name = TextDatumGetCString(datum_opts[i]);
+			char	   *opt = TextDatumGetCString(datum_opts[i + 1]);
+
+			options = lappend(options, makeDefElem(name, (Node *) makeString(opt), -1));
+		}
+	}
+
+	InitMaterializedSRF(fcinfo, 0);
+	p->tupstore = rsinfo->setResult;
+	p->tupdesc = rsinfo->setDesc;
+
+	/*
+	 * Compute the current end-of-wal.
+	 */
+	if (!RecoveryInProgress())
+		end_of_wal = GetFlushRecPtr(NULL);
+	else
+		end_of_wal = GetXLogReplayRecPtr(NULL);
+
+	ReplicationSlotAcquire(NameStr(*name), true);
+
+	PG_TRY();
+	{
+		/* restart at slot's confirmed_flush */
+		ctx = CreateDecodingContext(InvalidXLogRecPtr,
+									options,
+									false,
+									XL_ROUTINE(.page_read = read_local_xlog_page,
+											   .segment_open = wal_segment_open,
+											   .segment_close = wal_segment_close),
+									LogicalOutputPrepareWrite,
+									LogicalOutputWrite, NULL);
+
+		MemoryContextSwitchTo(oldcontext);
+
+		/*
+		 * Check whether the output plugin writes textual output if that's
+		 * what we need.
+		 */
+		if (!binary &&
+			ctx->options.output_type !=OUTPUT_PLUGIN_TEXTUAL_OUTPUT)
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					 errmsg("logical decoding output plugin \"%s\" produces binary output, but function \"%s\" expects textual data",
+							NameStr(MyReplicationSlot->data.plugin),
+							format_procedure(fcinfo->flinfo->fn_oid))));
+
+		ctx->output_writer_private = p;
+
+		/*
+		 * Decoding of WAL must start at restart_lsn so that the entirety of
+		 * xacts that committed after the slot's confirmed_flush can be
+		 * accumulated into reorder buffers.
+		 */
+		XLogBeginRead(ctx->reader, MyReplicationSlot->data.restart_lsn);
+
+		/* invalidate non-timetravel entries */
+		InvalidateSystemCaches();
+
+		/* Decode until we run out of records */
+		while (ctx->reader->EndRecPtr < end_of_wal)
+		{
+			XLogRecord *record;
+			char	   *errm = NULL;
+
+			record = XLogReadRecord(ctx->reader, &errm);
+			if (errm)
+				elog(ERROR, "could not find record for logical decoding: %s", errm);
+
+			/*
+			 * The {begin_txn,change,commit_txn}_wrapper callbacks above will
+			 * store the description into our tuplestore.
+			 */
+			if (record != NULL)
+				LogicalDecodingProcessRecord(ctx, ctx->reader);
+
+			/* check limits */
+			if (upto_lsn != InvalidXLogRecPtr &&
+				upto_lsn <= ctx->reader->EndRecPtr)
+				break;
+			if (upto_nchanges != 0 &&
+				upto_nchanges <= p->returned_rows)
+				break;
+			CHECK_FOR_INTERRUPTS();
+		}
+
+		/*
+		 * Logical decoding could have clobbered CurrentResourceOwner during
+		 * transaction management, so restore the executor's value.  (This is
+		 * a kluge, but it's not worth cleaning up right now.)
+		 */
+		CurrentResourceOwner = old_resowner;
+
+		/*
+		 * Next time, start where we left off. (Hunting things, the family
+		 * business..)
+		 */
+		if (ctx->reader->EndRecPtr != InvalidXLogRecPtr && confirm)
+		{
+			LogicalConfirmReceivedLocation(ctx->reader->EndRecPtr);
+
+			/*
+			 * If only the confirmed_flush_lsn has changed the slot won't get
+			 * marked as dirty by the above. Callers on the walsender
+			 * interface are expected to keep track of their own progress and
+			 * don't need it written out. But SQL-interface users cannot
+			 * specify their own start positions and it's harder for them to
+			 * keep track of their progress, so we should make more of an
+			 * effort to save it for them.
+			 *
+			 * Dirty the slot so it's written out at the next checkpoint.
+			 * We'll still lose its position on crash, as documented, but it's
+			 * better than always losing the position even on clean restart.
+			 */
+			ReplicationSlotMarkDirty();
+		}
+
+		/* free context, call shutdown callback */
+		FreeDecodingContext(ctx);
+
+		ReplicationSlotRelease();
+		InvalidateSystemCaches();
+	}
+	PG_CATCH();
+	{
+		/* clear all timetravel entries */
+		InvalidateSystemCaches();
+
+		PG_RE_THROW();
+	}
+	PG_END_TRY();
+
+	return (Datum) 0;
+}
+
+/*
+ * SQL function returning the changestream as text, consuming the data.
+ */
+Datum
+pg_logical_slot_get_changes(PG_FUNCTION_ARGS)
+{
+	return pg_logical_slot_get_changes_guts(fcinfo, true, false);
+}
+
+/*
+ * SQL function returning the changestream as text, only peeking ahead.
+ */
+Datum
+pg_logical_slot_peek_changes(PG_FUNCTION_ARGS)
+{
+	return pg_logical_slot_get_changes_guts(fcinfo, false, false);
+}
+
+/*
+ * SQL function returning the changestream in binary, consuming the data.
+ */
+Datum
+pg_logical_slot_get_binary_changes(PG_FUNCTION_ARGS)
+{
+	return pg_logical_slot_get_changes_guts(fcinfo, true, true);
+}
+
+/*
+ * SQL function returning the changestream in binary, only peeking ahead.
+ */
+Datum
+pg_logical_slot_peek_binary_changes(PG_FUNCTION_ARGS)
+{
+	return pg_logical_slot_get_changes_guts(fcinfo, false, true);
+}
+
+
+/*
+ * SQL function for writing logical decoding message into WAL.
+ */
+Datum
+pg_logical_emit_message_bytea(PG_FUNCTION_ARGS)
+{
+	bool		transactional = PG_GETARG_BOOL(0);
+	char	   *prefix = text_to_cstring(PG_GETARG_TEXT_PP(1));
+	bytea	   *data = PG_GETARG_BYTEA_PP(2);
+	XLogRecPtr	lsn;
+
+	lsn = LogLogicalMessage(prefix, VARDATA_ANY(data), VARSIZE_ANY_EXHDR(data),
+							transactional);
+	PG_RETURN_LSN(lsn);
+}
+
+Datum
+pg_logical_emit_message_text(PG_FUNCTION_ARGS)
+{
+	/* bytea and text are compatible */
+	return pg_logical_emit_message_bytea(fcinfo);
+}