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I found that half a dozen (nearly 5%) of our AllocSetContextCreate calls had typos in the context-sizing parameters. While none of these led to especially significant problems, they did create minor inefficiencies, and it's now clear that expecting people to copy-and-paste those calls accurately is not a great idea. Let's reduce the risk of future errors by introducing single macros that encapsulate the common use-cases. Three such macros are enough to cover all but two special-purpose contexts; those two calls can be left as-is, I think. While this patch doesn't in itself improve matters for third-party extensions, it doesn't break anything for them either, and they can gradually adopt the simplified notation over time. In passing, change TopMemoryContext to use the default allocation parameters. Formerly it could only be extended 8K at a time. That was probably reasonable when this code was written; but nowadays we create many more contexts than we did then, so that it's not unusual to have a couple hundred K in TopMemoryContext, even without considering various dubious code that sticks other things there. There seems no good reason not to let it use growing blocks like most other contexts. Back-patch to 9.6, mostly because that's still close enough to HEAD that it's easy to do so, and keeping the branches in sync can be expected to avoid some future back-patching pain. The bugs fixed by these changes don't seem to be significant enough to justify fixing them further back. Discussion: <21072.1472321324@sss.pgh.pa.us>
490 lines
13 KiB
C
490 lines
13 KiB
C
/*-------------------------------------------------------------------------
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*
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* test_decoding.c
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* example logical decoding output plugin
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*
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* Copyright (c) 2012-2016, PostgreSQL Global Development Group
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*
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* IDENTIFICATION
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* contrib/test_decoding/test_decoding.c
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*
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*-------------------------------------------------------------------------
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*/
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#include "postgres.h"
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#include "access/sysattr.h"
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#include "catalog/pg_class.h"
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#include "catalog/pg_type.h"
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#include "nodes/parsenodes.h"
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#include "replication/output_plugin.h"
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#include "replication/logical.h"
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#include "replication/message.h"
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#include "replication/origin.h"
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#include "utils/builtins.h"
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#include "utils/lsyscache.h"
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#include "utils/memutils.h"
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#include "utils/rel.h"
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#include "utils/relcache.h"
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#include "utils/syscache.h"
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#include "utils/typcache.h"
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PG_MODULE_MAGIC;
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/* These must be available to pg_dlsym() */
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extern void _PG_init(void);
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extern void _PG_output_plugin_init(OutputPluginCallbacks *cb);
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typedef struct
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{
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MemoryContext context;
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bool include_xids;
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bool include_timestamp;
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bool skip_empty_xacts;
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bool xact_wrote_changes;
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bool only_local;
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} TestDecodingData;
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static void pg_decode_startup(LogicalDecodingContext *ctx, OutputPluginOptions *opt,
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bool is_init);
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static void pg_decode_shutdown(LogicalDecodingContext *ctx);
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static void pg_decode_begin_txn(LogicalDecodingContext *ctx,
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ReorderBufferTXN *txn);
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static void pg_output_begin(LogicalDecodingContext *ctx,
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TestDecodingData *data,
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ReorderBufferTXN *txn,
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bool last_write);
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static void pg_decode_commit_txn(LogicalDecodingContext *ctx,
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ReorderBufferTXN *txn, XLogRecPtr commit_lsn);
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static void pg_decode_change(LogicalDecodingContext *ctx,
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ReorderBufferTXN *txn, Relation rel,
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ReorderBufferChange *change);
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static bool pg_decode_filter(LogicalDecodingContext *ctx,
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RepOriginId origin_id);
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static void pg_decode_message(LogicalDecodingContext *ctx,
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ReorderBufferTXN *txn, XLogRecPtr message_lsn,
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bool transactional, const char *prefix,
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Size sz, const char *message);
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void
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_PG_init(void)
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{
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/* other plugins can perform things here */
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}
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/* specify output plugin callbacks */
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void
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_PG_output_plugin_init(OutputPluginCallbacks *cb)
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{
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AssertVariableIsOfType(&_PG_output_plugin_init, LogicalOutputPluginInit);
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cb->startup_cb = pg_decode_startup;
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cb->begin_cb = pg_decode_begin_txn;
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cb->change_cb = pg_decode_change;
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cb->commit_cb = pg_decode_commit_txn;
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cb->filter_by_origin_cb = pg_decode_filter;
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cb->shutdown_cb = pg_decode_shutdown;
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cb->message_cb = pg_decode_message;
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}
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/* initialize this plugin */
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static void
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pg_decode_startup(LogicalDecodingContext *ctx, OutputPluginOptions *opt,
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bool is_init)
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{
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ListCell *option;
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TestDecodingData *data;
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data = palloc0(sizeof(TestDecodingData));
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data->context = AllocSetContextCreate(ctx->context,
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"text conversion context",
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ALLOCSET_DEFAULT_SIZES);
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data->include_xids = true;
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data->include_timestamp = false;
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data->skip_empty_xacts = false;
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data->only_local = false;
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ctx->output_plugin_private = data;
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opt->output_type = OUTPUT_PLUGIN_TEXTUAL_OUTPUT;
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foreach(option, ctx->output_plugin_options)
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{
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DefElem *elem = lfirst(option);
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Assert(elem->arg == NULL || IsA(elem->arg, String));
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if (strcmp(elem->defname, "include-xids") == 0)
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{
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/* if option does not provide a value, it means its value is true */
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if (elem->arg == NULL)
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data->include_xids = true;
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else if (!parse_bool(strVal(elem->arg), &data->include_xids))
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ereport(ERROR,
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(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
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errmsg("could not parse value \"%s\" for parameter \"%s\"",
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strVal(elem->arg), elem->defname)));
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}
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else if (strcmp(elem->defname, "include-timestamp") == 0)
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{
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if (elem->arg == NULL)
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data->include_timestamp = true;
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else if (!parse_bool(strVal(elem->arg), &data->include_timestamp))
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ereport(ERROR,
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(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
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errmsg("could not parse value \"%s\" for parameter \"%s\"",
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strVal(elem->arg), elem->defname)));
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}
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else if (strcmp(elem->defname, "force-binary") == 0)
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{
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bool force_binary;
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if (elem->arg == NULL)
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continue;
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else if (!parse_bool(strVal(elem->arg), &force_binary))
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ereport(ERROR,
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(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
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errmsg("could not parse value \"%s\" for parameter \"%s\"",
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strVal(elem->arg), elem->defname)));
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if (force_binary)
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opt->output_type = OUTPUT_PLUGIN_BINARY_OUTPUT;
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}
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else if (strcmp(elem->defname, "skip-empty-xacts") == 0)
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{
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if (elem->arg == NULL)
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data->skip_empty_xacts = true;
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else if (!parse_bool(strVal(elem->arg), &data->skip_empty_xacts))
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ereport(ERROR,
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(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
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errmsg("could not parse value \"%s\" for parameter \"%s\"",
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strVal(elem->arg), elem->defname)));
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}
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else if (strcmp(elem->defname, "only-local") == 0)
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{
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if (elem->arg == NULL)
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data->only_local = true;
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else if (!parse_bool(strVal(elem->arg), &data->only_local))
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ereport(ERROR,
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(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
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errmsg("could not parse value \"%s\" for parameter \"%s\"",
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strVal(elem->arg), elem->defname)));
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}
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else
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{
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ereport(ERROR,
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(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
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errmsg("option \"%s\" = \"%s\" is unknown",
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elem->defname,
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elem->arg ? strVal(elem->arg) : "(null)")));
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}
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}
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}
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/* cleanup this plugin's resources */
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static void
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pg_decode_shutdown(LogicalDecodingContext *ctx)
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{
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TestDecodingData *data = ctx->output_plugin_private;
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/* cleanup our own resources via memory context reset */
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MemoryContextDelete(data->context);
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}
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/* BEGIN callback */
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static void
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pg_decode_begin_txn(LogicalDecodingContext *ctx, ReorderBufferTXN *txn)
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{
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TestDecodingData *data = ctx->output_plugin_private;
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data->xact_wrote_changes = false;
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if (data->skip_empty_xacts)
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return;
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pg_output_begin(ctx, data, txn, true);
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}
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static void
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pg_output_begin(LogicalDecodingContext *ctx, TestDecodingData *data, ReorderBufferTXN *txn, bool last_write)
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{
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OutputPluginPrepareWrite(ctx, last_write);
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if (data->include_xids)
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appendStringInfo(ctx->out, "BEGIN %u", txn->xid);
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else
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appendStringInfoString(ctx->out, "BEGIN");
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OutputPluginWrite(ctx, last_write);
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}
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/* COMMIT callback */
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static void
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pg_decode_commit_txn(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
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XLogRecPtr commit_lsn)
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{
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TestDecodingData *data = ctx->output_plugin_private;
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if (data->skip_empty_xacts && !data->xact_wrote_changes)
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return;
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OutputPluginPrepareWrite(ctx, true);
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if (data->include_xids)
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appendStringInfo(ctx->out, "COMMIT %u", txn->xid);
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else
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appendStringInfoString(ctx->out, "COMMIT");
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if (data->include_timestamp)
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appendStringInfo(ctx->out, " (at %s)",
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timestamptz_to_str(txn->commit_time));
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OutputPluginWrite(ctx, true);
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}
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static bool
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pg_decode_filter(LogicalDecodingContext *ctx,
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RepOriginId origin_id)
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{
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TestDecodingData *data = ctx->output_plugin_private;
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if (data->only_local && origin_id != InvalidRepOriginId)
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return true;
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return false;
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}
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/*
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* Print literal `outputstr' already represented as string of type `typid'
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* into stringbuf `s'.
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*
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* Some builtin types aren't quoted, the rest is quoted. Escaping is done as
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* if standard_conforming_strings were enabled.
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*/
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static void
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print_literal(StringInfo s, Oid typid, char *outputstr)
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{
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const char *valptr;
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switch (typid)
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{
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case INT2OID:
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case INT4OID:
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case INT8OID:
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case OIDOID:
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case FLOAT4OID:
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case FLOAT8OID:
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case NUMERICOID:
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/* NB: We don't care about Inf, NaN et al. */
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appendStringInfoString(s, outputstr);
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break;
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case BITOID:
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case VARBITOID:
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appendStringInfo(s, "B'%s'", outputstr);
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break;
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case BOOLOID:
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if (strcmp(outputstr, "t") == 0)
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appendStringInfoString(s, "true");
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else
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appendStringInfoString(s, "false");
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break;
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default:
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appendStringInfoChar(s, '\'');
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for (valptr = outputstr; *valptr; valptr++)
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{
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char ch = *valptr;
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if (SQL_STR_DOUBLE(ch, false))
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appendStringInfoChar(s, ch);
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appendStringInfoChar(s, ch);
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}
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appendStringInfoChar(s, '\'');
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break;
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}
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}
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/* print the tuple 'tuple' into the StringInfo s */
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static void
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tuple_to_stringinfo(StringInfo s, TupleDesc tupdesc, HeapTuple tuple, bool skip_nulls)
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{
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int natt;
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Oid oid;
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/* print oid of tuple, it's not included in the TupleDesc */
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if ((oid = HeapTupleHeaderGetOid(tuple->t_data)) != InvalidOid)
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{
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appendStringInfo(s, " oid[oid]:%u", oid);
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}
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/* print all columns individually */
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for (natt = 0; natt < tupdesc->natts; natt++)
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{
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Form_pg_attribute attr; /* the attribute itself */
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Oid typid; /* type of current attribute */
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Oid typoutput; /* output function */
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bool typisvarlena;
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Datum origval; /* possibly toasted Datum */
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bool isnull; /* column is null? */
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attr = tupdesc->attrs[natt];
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/*
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* don't print dropped columns, we can't be sure everything is
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* available for them
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*/
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if (attr->attisdropped)
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continue;
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/*
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* Don't print system columns, oid will already have been printed if
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* present.
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*/
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if (attr->attnum < 0)
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continue;
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typid = attr->atttypid;
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/* get Datum from tuple */
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origval = heap_getattr(tuple, natt + 1, tupdesc, &isnull);
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if (isnull && skip_nulls)
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continue;
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/* print attribute name */
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appendStringInfoChar(s, ' ');
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appendStringInfoString(s, quote_identifier(NameStr(attr->attname)));
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/* print attribute type */
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appendStringInfoChar(s, '[');
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appendStringInfoString(s, format_type_be(typid));
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appendStringInfoChar(s, ']');
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/* query output function */
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getTypeOutputInfo(typid,
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&typoutput, &typisvarlena);
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/* print separator */
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appendStringInfoChar(s, ':');
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/* print data */
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if (isnull)
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appendStringInfoString(s, "null");
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else if (typisvarlena && VARATT_IS_EXTERNAL_ONDISK(origval))
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appendStringInfoString(s, "unchanged-toast-datum");
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else if (!typisvarlena)
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print_literal(s, typid,
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OidOutputFunctionCall(typoutput, origval));
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else
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{
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Datum val; /* definitely detoasted Datum */
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val = PointerGetDatum(PG_DETOAST_DATUM(origval));
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print_literal(s, typid, OidOutputFunctionCall(typoutput, val));
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}
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}
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}
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/*
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* callback for individual changed tuples
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*/
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static void
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pg_decode_change(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
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Relation relation, ReorderBufferChange *change)
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{
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TestDecodingData *data;
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Form_pg_class class_form;
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TupleDesc tupdesc;
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MemoryContext old;
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data = ctx->output_plugin_private;
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/* output BEGIN if we haven't yet */
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if (data->skip_empty_xacts && !data->xact_wrote_changes)
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{
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pg_output_begin(ctx, data, txn, false);
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}
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data->xact_wrote_changes = true;
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class_form = RelationGetForm(relation);
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tupdesc = RelationGetDescr(relation);
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/* Avoid leaking memory by using and resetting our own context */
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old = MemoryContextSwitchTo(data->context);
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OutputPluginPrepareWrite(ctx, true);
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appendStringInfoString(ctx->out, "table ");
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appendStringInfoString(ctx->out,
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quote_qualified_identifier(
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get_namespace_name(
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get_rel_namespace(RelationGetRelid(relation))),
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NameStr(class_form->relname)));
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appendStringInfoChar(ctx->out, ':');
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switch (change->action)
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{
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case REORDER_BUFFER_CHANGE_INSERT:
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appendStringInfoString(ctx->out, " INSERT:");
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if (change->data.tp.newtuple == NULL)
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appendStringInfoString(ctx->out, " (no-tuple-data)");
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else
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tuple_to_stringinfo(ctx->out, tupdesc,
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&change->data.tp.newtuple->tuple,
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false);
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break;
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case REORDER_BUFFER_CHANGE_UPDATE:
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appendStringInfoString(ctx->out, " UPDATE:");
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if (change->data.tp.oldtuple != NULL)
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{
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appendStringInfoString(ctx->out, " old-key:");
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tuple_to_stringinfo(ctx->out, tupdesc,
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&change->data.tp.oldtuple->tuple,
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true);
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appendStringInfoString(ctx->out, " new-tuple:");
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}
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if (change->data.tp.newtuple == NULL)
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appendStringInfoString(ctx->out, " (no-tuple-data)");
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else
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tuple_to_stringinfo(ctx->out, tupdesc,
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&change->data.tp.newtuple->tuple,
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false);
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break;
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case REORDER_BUFFER_CHANGE_DELETE:
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appendStringInfoString(ctx->out, " DELETE:");
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/* if there was no PK, we only know that a delete happened */
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if (change->data.tp.oldtuple == NULL)
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appendStringInfoString(ctx->out, " (no-tuple-data)");
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/* In DELETE, only the replica identity is present; display that */
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else
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tuple_to_stringinfo(ctx->out, tupdesc,
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&change->data.tp.oldtuple->tuple,
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true);
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break;
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default:
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Assert(false);
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}
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MemoryContextSwitchTo(old);
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MemoryContextReset(data->context);
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OutputPluginWrite(ctx, true);
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}
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static void
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pg_decode_message(LogicalDecodingContext *ctx,
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ReorderBufferTXN *txn, XLogRecPtr lsn, bool transactional,
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const char *prefix, Size sz, const char *message)
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{
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OutputPluginPrepareWrite(ctx, true);
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appendStringInfo(ctx->out, "message: transactional: %d prefix: %s, sz: %zu content:",
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transactional, prefix, sz);
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appendBinaryStringInfo(ctx->out, message, sz);
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OutputPluginWrite(ctx, true);
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}
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