Commit 0aa8a01d authored by Amit Kapila's avatar Amit Kapila
Browse files

Extend the output plugin API to allow decoding of prepared xacts.

This adds six methods to the output plugin API, adding support for
streaming changes of two-phase transactions at prepare time.

* begin_prepare
* filter_prepare
* prepare
* commit_prepared
* rollback_prepared
* stream_prepare

Most of this is a simple extension of the existing methods, with the
semantic difference that the transaction is not yet committed and maybe
aborted later.

Until now two-phase transactions were translated into regular transactions
on the subscriber, and the GID was not forwarded to it. None of the
two-phase commands were communicated to the subscriber.

This patch provides the infrastructure for logical decoding plugins to be
informed of two-phase commands Like PREPARE TRANSACTION, COMMIT PREPARED
and ROLLBACK PREPARED commands with the corresponding GID.

This also extends the 'test_decoding' plugin, implementing these new
methods.

This commit simply adds these new APIs and the upcoming patch to "allow
the decoding at prepare time in ReorderBuffer" will use these APIs.

Author: Ajin Cherian and Amit Kapila based on previous work by Nikhil Sontakke and Stas Kelvich
Reviewed-by: Amit Kapila, Peter Smith, Sawada Masahiko, and Dilip Kumar
Discussion:
https://postgr.es/m/02DA5F5E-CECE-4D9C-8B4B-418077E2C010@postgrespro.ru
https://postgr.es/m/CAMGcDxeqEpWj3fTXwqhSwBdXd2RS9jzwWscO-XbeCfso6ts3+Q@mail.gmail.com
parent fa744697
......@@ -76,6 +76,20 @@ static void pg_decode_message(LogicalDecodingContext *ctx,
ReorderBufferTXN *txn, XLogRecPtr message_lsn,
bool transactional, const char *prefix,
Size sz, const char *message);
static bool pg_decode_filter_prepare(LogicalDecodingContext *ctx,
const char *gid);
static void pg_decode_begin_prepare_txn(LogicalDecodingContext *ctx,
ReorderBufferTXN *txn);
static void pg_decode_prepare_txn(LogicalDecodingContext *ctx,
ReorderBufferTXN *txn,
XLogRecPtr prepare_lsn);
static void pg_decode_commit_prepared_txn(LogicalDecodingContext *ctx,
ReorderBufferTXN *txn,
XLogRecPtr commit_lsn);
static void pg_decode_rollback_prepared_txn(LogicalDecodingContext *ctx,
ReorderBufferTXN *txn,
XLogRecPtr prepare_end_lsn,
TimestampTz prepare_time);
static void pg_decode_stream_start(LogicalDecodingContext *ctx,
ReorderBufferTXN *txn);
static void pg_output_stream_start(LogicalDecodingContext *ctx,
......@@ -87,6 +101,9 @@ static void pg_decode_stream_stop(LogicalDecodingContext *ctx,
static void pg_decode_stream_abort(LogicalDecodingContext *ctx,
ReorderBufferTXN *txn,
XLogRecPtr abort_lsn);
static void pg_decode_stream_prepare(LogicalDecodingContext *ctx,
ReorderBufferTXN *txn,
XLogRecPtr prepare_lsn);
static void pg_decode_stream_commit(LogicalDecodingContext *ctx,
ReorderBufferTXN *txn,
XLogRecPtr commit_lsn);
......@@ -123,9 +140,15 @@ _PG_output_plugin_init(OutputPluginCallbacks *cb)
cb->filter_by_origin_cb = pg_decode_filter;
cb->shutdown_cb = pg_decode_shutdown;
cb->message_cb = pg_decode_message;
cb->filter_prepare_cb = pg_decode_filter_prepare;
cb->begin_prepare_cb = pg_decode_begin_prepare_txn;
cb->prepare_cb = pg_decode_prepare_txn;
cb->commit_prepared_cb = pg_decode_commit_prepared_txn;
cb->rollback_prepared_cb = pg_decode_rollback_prepared_txn;
cb->stream_start_cb = pg_decode_stream_start;
cb->stream_stop_cb = pg_decode_stream_stop;
cb->stream_abort_cb = pg_decode_stream_abort;
cb->stream_prepare_cb = pg_decode_stream_prepare;
cb->stream_commit_cb = pg_decode_stream_commit;
cb->stream_change_cb = pg_decode_stream_change;
cb->stream_message_cb = pg_decode_stream_message;
......@@ -141,6 +164,7 @@ pg_decode_startup(LogicalDecodingContext *ctx, OutputPluginOptions *opt,
ListCell *option;
TestDecodingData *data;
bool enable_streaming = false;
bool enable_twophase = false;
data = palloc0(sizeof(TestDecodingData));
data->context = AllocSetContextCreate(ctx->context,
......@@ -241,6 +265,16 @@ pg_decode_startup(LogicalDecodingContext *ctx, OutputPluginOptions *opt,
errmsg("could not parse value \"%s\" for parameter \"%s\"",
strVal(elem->arg), elem->defname)));
}
else if (strcmp(elem->defname, "two-phase-commit") == 0)
{
if (elem->arg == NULL)
continue;
else if (!parse_bool(strVal(elem->arg), &enable_twophase))
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("could not parse value \"%s\" for parameter \"%s\"",
strVal(elem->arg), elem->defname)));
}
else
{
ereport(ERROR,
......@@ -252,6 +286,7 @@ pg_decode_startup(LogicalDecodingContext *ctx, OutputPluginOptions *opt,
}
ctx->streaming &= enable_streaming;
ctx->twophase &= enable_twophase;
}
/* cleanup this plugin's resources */
......@@ -320,6 +355,111 @@ pg_decode_commit_txn(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
OutputPluginWrite(ctx, true);
}
/* BEGIN PREPARE callback */
static void
pg_decode_begin_prepare_txn(LogicalDecodingContext *ctx, ReorderBufferTXN *txn)
{
TestDecodingData *data = ctx->output_plugin_private;
TestDecodingTxnData *txndata =
MemoryContextAllocZero(ctx->context, sizeof(TestDecodingTxnData));
txndata->xact_wrote_changes = false;
txn->output_plugin_private = txndata;
if (data->skip_empty_xacts)
return;
pg_output_begin(ctx, data, txn, true);
}
/* PREPARE callback */
static void
pg_decode_prepare_txn(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
XLogRecPtr prepare_lsn)
{
TestDecodingData *data = ctx->output_plugin_private;
TestDecodingTxnData *txndata = txn->output_plugin_private;
if (data->skip_empty_xacts && !txndata->xact_wrote_changes)
return;
OutputPluginPrepareWrite(ctx, true);
appendStringInfo(ctx->out, "PREPARE TRANSACTION %s",
quote_literal_cstr(txn->gid));
if (data->include_xids)
appendStringInfo(ctx->out, ", txid %u", txn->xid);
if (data->include_timestamp)
appendStringInfo(ctx->out, " (at %s)",
timestamptz_to_str(txn->commit_time));
OutputPluginWrite(ctx, true);
}
/* COMMIT PREPARED callback */
static void
pg_decode_commit_prepared_txn(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
XLogRecPtr commit_lsn)
{
TestDecodingData *data = ctx->output_plugin_private;
OutputPluginPrepareWrite(ctx, true);
appendStringInfo(ctx->out, "COMMIT PREPARED %s",
quote_literal_cstr(txn->gid));
if (data->include_xids)
appendStringInfo(ctx->out, ", txid %u", txn->xid);
if (data->include_timestamp)
appendStringInfo(ctx->out, " (at %s)",
timestamptz_to_str(txn->commit_time));
OutputPluginWrite(ctx, true);
}
/* ROLLBACK PREPARED callback */
static void
pg_decode_rollback_prepared_txn(LogicalDecodingContext *ctx,
ReorderBufferTXN *txn,
XLogRecPtr prepare_end_lsn,
TimestampTz prepare_time)
{
TestDecodingData *data = ctx->output_plugin_private;
OutputPluginPrepareWrite(ctx, true);
appendStringInfo(ctx->out, "ROLLBACK PREPARED %s",
quote_literal_cstr(txn->gid));
if (data->include_xids)
appendStringInfo(ctx->out, ", txid %u", txn->xid);
if (data->include_timestamp)
appendStringInfo(ctx->out, " (at %s)",
timestamptz_to_str(txn->commit_time));
OutputPluginWrite(ctx, true);
}
/*
* Filter out two-phase transactions.
*
* Each plugin can implement its own filtering logic. Here we demonstrate a
* simple logic by checking the GID. If the GID contains the "_nodecode"
* substring, then we filter it out.
*/
static bool
pg_decode_filter_prepare(LogicalDecodingContext *ctx, const char *gid)
{
if (strstr(gid, "_nodecode") != NULL)
return true;
return false;
}
static bool
pg_decode_filter(LogicalDecodingContext *ctx,
RepOriginId origin_id)
......@@ -701,6 +841,33 @@ pg_decode_stream_abort(LogicalDecodingContext *ctx,
OutputPluginWrite(ctx, true);
}
static void
pg_decode_stream_prepare(LogicalDecodingContext *ctx,
ReorderBufferTXN *txn,
XLogRecPtr prepare_lsn)
{
TestDecodingData *data = ctx->output_plugin_private;
TestDecodingTxnData *txndata = txn->output_plugin_private;
if (data->skip_empty_xacts && !txndata->xact_wrote_changes)
return;
OutputPluginPrepareWrite(ctx, true);
if (data->include_xids)
appendStringInfo(ctx->out, "preparing streamed transaction TXN %s, txid %u",
quote_literal_cstr(txn->gid), txn->xid);
else
appendStringInfo(ctx->out, "preparing streamed transaction %s",
quote_literal_cstr(txn->gid));
if (data->include_timestamp)
appendStringInfo(ctx->out, " (at %s)",
timestamptz_to_str(txn->commit_time));
OutputPluginWrite(ctx, true);
}
static void
pg_decode_stream_commit(LogicalDecodingContext *ctx,
ReorderBufferTXN *txn,
......
......@@ -389,9 +389,15 @@ typedef struct OutputPluginCallbacks
LogicalDecodeMessageCB message_cb;
LogicalDecodeFilterByOriginCB filter_by_origin_cb;
LogicalDecodeShutdownCB shutdown_cb;
LogicalDecodeFilterPrepareCB filter_prepare_cb;
LogicalDecodeBeginPrepareCB begin_prepare_cb;
LogicalDecodePrepareCB prepare_cb;
LogicalDecodeCommitPreparedCB commit_prepared_cb;
LogicalDecodeRollbackPreparedCB rollback_prepared_cb;
LogicalDecodeStreamStartCB stream_start_cb;
LogicalDecodeStreamStopCB stream_stop_cb;
LogicalDecodeStreamAbortCB stream_abort_cb;
LogicalDecodeStreamPrepareCB stream_prepare_cb;
LogicalDecodeStreamCommitCB stream_commit_cb;
LogicalDecodeStreamChangeCB stream_change_cb;
LogicalDecodeStreamMessageCB stream_message_cb;
......@@ -413,10 +419,20 @@ typedef void (*LogicalOutputPluginInit) (struct OutputPluginCallbacks *cb);
An output plugin may also define functions to support streaming of large,
in-progress transactions. The <function>stream_start_cb</function>,
<function>stream_stop_cb</function>, <function>stream_abort_cb</function>,
<function>stream_commit_cb</function> and <function>stream_change_cb</function>
<function>stream_commit_cb</function>, <function>stream_change_cb</function>,
and <function>stream_prepare_cb</function>
are required, while <function>stream_message_cb</function> and
<function>stream_truncate_cb</function> are optional.
</para>
<para>
An output plugin may also define functions to support two-phase commits,
which allows actions to be decoded on the <command>PREPARE TRANSACTION</command>.
The <function>begin_prepare_cb</function>, <function>prepare_cb</function>,
<function>stream_prepare_cb</function>,
<function>commit_prepared_cb</function> and <function>rollback_prepared_cb</function>
callbacks are required, while <function>filter_prepare_cb</function> is optional.
</para>
</sect2>
<sect2 id="logicaldecoding-capabilities">
......@@ -477,7 +493,15 @@ CREATE TABLE another_catalog_table(data text) WITH (user_catalog_table = true);
never get
decoded. Successful savepoints are
folded into the transaction containing them in the order they were
executed within that transaction.
executed within that transaction. A transaction that is prepared for
a two-phase commit using <command>PREPARE TRANSACTION</command> will
also be decoded if the output plugin callbacks needed for decoding
them are provided. It is possible that the current transaction which
is being decoded is aborted concurrently via a <command>ROLLBACK PREPARED</command>
command. In that case, the logical decoding of this transaction will
be aborted too. We will skip all the changes of such a transaction once
the abort is detected and abort the transaction when we read WAL for
<command>ROLLBACK PREPARED</command>.
</para>
<note>
......@@ -587,7 +611,13 @@ typedef void (*LogicalDecodeCommitCB) (struct LogicalDecodingContext *ctx,
an <command>INSERT</command>, <command>UPDATE</command>,
or <command>DELETE</command>. Even if the original command modified
several rows at once the callback will be called individually for each
row.
row. The <function>change_cb</function> callback may access system or
user catalog tables to aid in the process of outputting the row
modification details. In case of decoding a prepared (but yet
uncommitted) transaction or decoding of an uncommitted transaction, this
change callback might also error out due to simultaneous rollback of
this very same transaction. In that case, the logical decoding of this
aborted transaction is stopped gracefully.
<programlisting>
typedef void (*LogicalDecodeChangeCB) (struct LogicalDecodingContext *ctx,
ReorderBufferTXN *txn,
......@@ -685,7 +715,13 @@ typedef void (*LogicalDecodeMessageCB) (struct LogicalDecodingContext *ctx,
non-transactional and the XID was not assigned yet in the transaction
which logged the message. The <parameter>lsn</parameter> has WAL
location of the message. The <parameter>transactional</parameter> says
if the message was sent as transactional or not.
if the message was sent as transactional or not. Similar to the change
callback, in case of decoding a prepared (but yet uncommitted)
transaction or decoding of an uncommitted transaction, this message
callback might also error out due to simultaneous rollback of
this very same transaction. In that case, the logical decoding of this
aborted transaction is stopped gracefully.
The <parameter>prefix</parameter> is arbitrary null-terminated prefix
which can be used for identifying interesting messages for the current
plugin. And finally the <parameter>message</parameter> parameter holds
......@@ -698,6 +734,111 @@ typedef void (*LogicalDecodeMessageCB) (struct LogicalDecodingContext *ctx,
</para>
</sect3>
<sect3 id="logicaldecoding-output-plugin-filter-prepare">
<title>Prepare Filter Callback</title>
<para>
The optional <function>filter_prepare_cb</function> callback
is called to determine whether data that is part of the current
two-phase commit transaction should be considered for decode
at this prepare stage or as a regular one-phase transaction at
<command>COMMIT PREPARED</command> time later. To signal that
decoding should be skipped, return <literal>true</literal>;
<literal>false</literal> otherwise. When the callback is not
defined, <literal>false</literal> is assumed (i.e. nothing is
filtered).
<programlisting>
typedef bool (*LogicalDecodeFilterPrepareCB) (struct LogicalDecodingContext *ctx,
const char *gid);
</programlisting>
The <parameter>ctx</parameter> parameter has the same contents as for the
other callbacks. The <parameter>gid</parameter> is the identifier that later
identifies this transaction for <command>COMMIT PREPARED</command> or
<command>ROLLBACK PREPARED</command>.
</para>
<para>
The callback has to provide the same static answer for a given
<parameter>gid</parameter> every time it is called.
</para>
</sect3>
<sect3 id="logicaldecoding-output-plugin-begin-prepare">
<title>Transaction Begin Prepare Callback</title>
<para>
The required <function>begin_prepare_cb</function> callback is called
whenever the start of a prepared transaction has been decoded. The
<parameter>gid</parameter> field, which is part of the
<parameter>txn</parameter> parameter can be used in this callback to
check if the plugin has already received this prepare in which case it
can skip the remaining changes of the transaction. This can only happen
if the user restarts the decoding after receiving the prepare for a
transaction but before receiving the commit prepared say because of some
error.
<programlisting>
typedef void (*LogicalDecodeBeginPrepareCB) (struct LogicalDecodingContext *ctx,
ReorderBufferTXN *txn);
</programlisting>
</para>
</sect3>
<sect3 id="logicaldecoding-output-plugin-prepare">
<title>Transaction Prepare Callback</title>
<para>
The required <function>prepare_cb</function> callback is called whenever
a transaction which is prepared for two-phase commit has been
decoded. The <function>change_cb</function> callback for all modified
rows will have been called before this, if there have been any modified
rows. The <parameter>gid</parameter> field, which is part of the
<parameter>txn</parameter> parameter can be used in this callback.
<programlisting>
typedef void (*LogicalDecodePrepareCB) (struct LogicalDecodingContext *ctx,
ReorderBufferTXN *txn,
XLogRecPtr prepare_lsn);
</programlisting>
</para>
</sect3>
<sect3 id="logicaldecoding-output-plugin-commit-prepared">
<title>Transaction Commit Prepared Callback</title>
<para>
The required <function>commit_prepared_cb</function> callback is called
whenever a transaction commit prepared has been decoded. The
<parameter>gid</parameter> field, which is part of the
<parameter>txn</parameter> parameter can be used in this callback.
<programlisting>
typedef void (*LogicalDecodeCommitPreparedCB) (struct LogicalDecodingContext *ctx,
ReorderBufferTXN *txn,
XLogRecPtr commit_lsn);
</programlisting>
</para>
</sect3>
<sect3 id="logicaldecoding-output-plugin-rollback-prepared">
<title>Transaction Rollback Prepared Callback</title>
<para>
The required <function>rollback_prepared_cb</function> callback is called
whenever a transaction rollback prepared has been decoded. The
<parameter>gid</parameter> field, which is part of the
<parameter>txn</parameter> parameter can be used in this callback. The
parameters <parameter>prepare_end_lsn</parameter> and
<parameter>prepare_time</parameter> can be used to check if the plugin
has received this prepare transaction in which case it can apply the
rollback, otherwise, it can skip the rollback operation. The
<parameter>gid</parameter> alone is not sufficient because the downstream
node can have prepared transaction with same identifier.
<programlisting>
typedef void (*LogicalDecodeRollbackPreparedCB) (struct LogicalDecodingContext *ctx,
ReorderBufferTXN *txn,
XLogRecPtr preapre_end_lsn,
TimestampTz prepare_time);
</programlisting>
</para>
</sect3>
<sect3 id="logicaldecoding-output-plugin-stream-start">
<title>Stream Start Callback</title>
<para>
......@@ -735,6 +876,19 @@ typedef void (*LogicalDecodeStreamAbortCB) (struct LogicalDecodingContext *ctx,
</para>
</sect3>
<sect3 id="logicaldecoding-output-plugin-stream-prepare">
<title>Stream Prepare Callback</title>
<para>
The <function>stream_prepare_cb</function> callback is called to prepare
a previously streamed transaction as part of a two-phase commit.
<programlisting>
typedef void (*LogicalDecodeStreamPrepareCB) (struct LogicalDecodingContext *ctx,
ReorderBufferTXN *txn,
XLogRecPtr prepare_lsn);
</programlisting>
</para>
</sect3>
<sect3 id="logicaldecoding-output-plugin-stream-commit">
<title>Stream Commit Callback</title>
<para>
......@@ -913,9 +1067,13 @@ OutputPluginWrite(ctx, true);
When streaming an in-progress transaction, the changes (and messages) are
streamed in blocks demarcated by <function>stream_start_cb</function>
and <function>stream_stop_cb</function> callbacks. Once all the decoded
changes are transmitted, the transaction is committed using the
<function>stream_commit_cb</function> callback (or possibly aborted using
the <function>stream_abort_cb</function> callback).
changes are transmitted, the transaction can be committed using the
the <function>stream_commit_cb</function> callback
(or possibly aborted using the <function>stream_abort_cb</function> callback).
If two-phase commits are supported, the transaction can be prepared using the
<function>stream_prepare_cb</function> callback, commit prepared using the
<function>commit_prepared_cb</function> callback or aborted using the
<function>rollback_prepared_cb</function>.
</para>
<para>
......
......@@ -59,6 +59,13 @@ static void shutdown_cb_wrapper(LogicalDecodingContext *ctx);
static void begin_cb_wrapper(ReorderBuffer *cache, ReorderBufferTXN *txn);
static void commit_cb_wrapper(ReorderBuffer *cache, ReorderBufferTXN *txn,
XLogRecPtr commit_lsn);
static void begin_prepare_cb_wrapper(ReorderBuffer *cache, ReorderBufferTXN *txn);
static void prepare_cb_wrapper(ReorderBuffer *cache, ReorderBufferTXN *txn,
XLogRecPtr prepare_lsn);
static void commit_prepared_cb_wrapper(ReorderBuffer *cache, ReorderBufferTXN *txn,
XLogRecPtr commit_lsn);
static void rollback_prepared_cb_wrapper(ReorderBuffer *cache, ReorderBufferTXN *txn,
XLogRecPtr prepare_end_lsn, TimestampTz prepare_time);
static void change_cb_wrapper(ReorderBuffer *cache, ReorderBufferTXN *txn,
Relation relation, ReorderBufferChange *change);
static void truncate_cb_wrapper(ReorderBuffer *cache, ReorderBufferTXN *txn,
......@@ -74,6 +81,8 @@ static void stream_stop_cb_wrapper(ReorderBuffer *cache, ReorderBufferTXN *txn,
XLogRecPtr last_lsn);
static void stream_abort_cb_wrapper(ReorderBuffer *cache, ReorderBufferTXN *txn,
XLogRecPtr abort_lsn);
static void stream_prepare_cb_wrapper(ReorderBuffer *cache, ReorderBufferTXN *txn,
XLogRecPtr prepare_lsn);
static void stream_commit_cb_wrapper(ReorderBuffer *cache, ReorderBufferTXN *txn,
XLogRecPtr commit_lsn);
static void stream_change_cb_wrapper(ReorderBuffer *cache, ReorderBufferTXN *txn,
......@@ -237,11 +246,37 @@ StartupDecodingContext(List *output_plugin_options,
ctx->reorder->stream_start = stream_start_cb_wrapper;
ctx->reorder->stream_stop = stream_stop_cb_wrapper;
ctx->reorder->stream_abort = stream_abort_cb_wrapper;
ctx->reorder->stream_prepare = stream_prepare_cb_wrapper;
ctx->reorder->stream_commit = stream_commit_cb_wrapper;
ctx->reorder->stream_change = stream_change_cb_wrapper;
ctx->reorder->stream_message = stream_message_cb_wrapper;
ctx->reorder->stream_truncate = stream_truncate_cb_wrapper;
/*
* To support two-phase logical decoding, we require
* begin_prepare/prepare/commit-prepare/abort-prepare callbacks. The
* filter_prepare callback is optional. We however enable two-phase
* logical decoding when at least one of the methods is enabled so that we
* can easily identify missing methods.
*
* We decide it here, but only check it later in the wrappers.
*/
ctx->twophase = (ctx->callbacks.begin_prepare_cb != NULL) ||
(ctx->callbacks.prepare_cb != NULL) ||
(ctx->callbacks.commit_prepared_cb != NULL) ||
(ctx->callbacks.rollback_prepared_cb != NULL) ||
(ctx->callbacks.stream_prepare_cb != NULL) ||
(ctx->callbacks.filter_prepare_cb != NULL);
/*
* Callback to support decoding at prepare time.
*/
ctx->reorder->begin_prepare = begin_prepare_cb_wrapper;
ctx->reorder->prepare = prepare_cb_wrapper;
ctx->reorder->commit_prepared = commit_prepared_cb_wrapper;
ctx->reorder->rollback_prepared = rollback_prepared_cb_wrapper;
ctx->out = makeStringInfo();
ctx->prepare_write = prepare_write;
ctx->write = do_write;
......@@ -782,6 +817,186 @@ commit_cb_wrapper(ReorderBuffer *cache, ReorderBufferTXN *txn,
error_context_stack = errcallback.previous;
}
/*
* The functionality of begin_prepare is quite similar to begin with the
* exception that this will have gid (global transaction id) information which
* can be used by plugin. Now, we thought about extending the existing begin
* but that would break the replication protocol and additionally this looks
* cleaner.
*/
static void
begin_prepare_cb_wrapper(ReorderBuffer *cache, ReorderBufferTXN *txn)
{
LogicalDecodingContext *ctx = cache->private_data;
LogicalErrorCallbackState state;
ErrorContextCallback errcallback;
Assert(!ctx->fast_forward);
/* We're only supposed to call this when two-phase commits are supported */
Assert(ctx->twophase);
/* Push callback + info on the error context stack */
state.ctx = ctx;
state.callback_name = "begin_prepare";
state.report_location = txn->first_lsn;
errcallback.callback = output_plugin_error_callback;
errcallback.arg = (void *) &state;
errcallback.previous = error_context_stack;
error_context_stack = &errcallback;
/* set output state */
ctx->accept_writes = true;
ctx->write_xid = txn->xid;
ctx->write_location = txn->first_lsn;
/*
* If the plugin supports two-phase commits then begin prepare callback is
* mandatory
*/
if (ctx->callbacks.begin_prepare_cb == NULL)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("logical replication at prepare time requires begin_prepare_cb callback")));
/* do the actual work: call callback */
ctx->callbacks.begin_prepare_cb(ctx, txn);
/* Pop the error context stack */
error_context_stack = errcallback.previous;
}
static void
prepare_cb_wrapper(ReorderBuffer *cache, ReorderBufferTXN *txn,
XLogRecPtr prepare_lsn)
{
LogicalDecodingContext *ctx = cache->private_data;
LogicalErrorCallbackState state;
ErrorContextCallback errcallback;
Assert(!ctx->fast_forward);
/* We're only supposed to call this when two-phase commits are supported */
Assert(ctx->twophase);
/* Push callback + info on the error context stack */
state.ctx = ctx;
state.callback_name = "prepare";
state.report_location = txn->final_lsn; /* beginning of prepare record */
errcallback.callback = output_plugin_error_callback;
errcallback.arg = (void *) &state;
errcallback.previous = error_context_stack;
error_context_stack = &errcallback;
/* set output state */
ctx->accept_writes = true;
ctx->write_xid = txn->xid;
ctx->write_location = txn->end_lsn; /* points to the end of the record */
/*
* If the plugin supports two-phase commits then prepare callback is
* mandatory
*/
if (ctx->callbacks.prepare_cb == NULL)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("logical replication at prepare time requires prepare_cb callback")));
/* do the actual work: call callback */
ctx->callbacks.prepare_cb(ctx, txn, prepare_lsn);
/* Pop the error context stack */
error_context_stack = errcallback.