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postgres-decoderbufs/src/decoderbufs.c

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/*
* decoderbufs - PostgreSQL output plug-in for logical replication to Protocol
* Buffers
*
* Copyright (c) 2014 Xavier Stevens
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
*all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
#include <inttypes.h>
#include "postgres.h"
#include "funcapi.h"
#include "catalog/pg_class.h"
#include "catalog/pg_type.h"
#include "replication/output_plugin.h"
#include "replication/logical.h"
#include "utils/builtins.h"
#include "utils/lsyscache.h"
#include "utils/json.h"
#include "utils/memutils.h"
#include "utils/numeric.h"
#include "utils/rel.h"
#include "utils/relcache.h"
#include "utils/syscache.h"
#include "utils/typcache.h"
#include "proto/pg_logicaldec.pb-c.h"
PG_MODULE_MAGIC;
/* define a time macro to convert TimestampTz into something more sane,
* which in this case is microseconds since epoch
*/
#ifdef HAVE_INT64_TIMESTAMP
#define TIMESTAMPTZ_TO_USEC_SINCE_EPOCH(t) \
t + ((POSTGRES_EPOCH_JDATE - UNIX_EPOCH_JDATE) * SECS_PER_DAY *USECS_PER_SEC);
#else
#define TIMESTAMPTZ_TO_USEC_SINCE_EPOCH(t) \
(t + ((POSTGRES_EPOCH_JDATE - UNIX_EPOCH_JDATE) * SECS_PER_DAY)) * 1000.0;
#endif
typedef struct {
MemoryContext context;
bool debug_mode;
} DecoderData;
/* these must be available to pg_dlsym() */
extern void _PG_init(void);
extern void _PG_output_plugin_init(OutputPluginCallbacks *cb);
static void pg_decode_startup(LogicalDecodingContext *ctx,
OutputPluginOptions *opt, bool is_init);
static void pg_decode_shutdown(LogicalDecodingContext *ctx);
static void pg_decode_begin_txn(LogicalDecodingContext *ctx,
ReorderBufferTXN *txn);
static void pg_decode_commit_txn(LogicalDecodingContext *ctx,
ReorderBufferTXN *txn, XLogRecPtr commit_lsn);
static void pg_decode_change(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
Relation rel, ReorderBufferChange *change);
void _PG_init(void) {}
/* specify output plugin callbacks */
void _PG_output_plugin_init(OutputPluginCallbacks *cb) {
AssertVariableIsOfType(&_PG_output_plugin_init, LogicalOutputPluginInit);
cb->startup_cb = pg_decode_startup;
cb->begin_cb = pg_decode_begin_txn;
cb->change_cb = pg_decode_change;
cb->commit_cb = pg_decode_commit_txn;
cb->shutdown_cb = pg_decode_shutdown;
}
/* initialize this plugin */
static void pg_decode_startup(LogicalDecodingContext *ctx,
OutputPluginOptions *opt, bool is_init) {
ListCell *option;
DecoderData *data;
data = palloc(sizeof(DecoderData));
data->context = AllocSetContextCreate(
ctx->context, "decoderbufs context", ALLOCSET_DEFAULT_MINSIZE,
ALLOCSET_DEFAULT_INITSIZE, ALLOCSET_DEFAULT_MAXSIZE);
ctx->output_plugin_private = data;
opt->output_type = OUTPUT_PLUGIN_BINARY_OUTPUT;
foreach(option, ctx->output_plugin_options) {
DefElem *elem = lfirst(option);
Assert(elem->arg == NULL || IsA(elem->arg, String));
if (strcmp(elem->defname, "debug-mode") == 0) {
if (elem->arg == NULL)
data->debug_mode = false;
else if (!parse_bool(strVal(elem->arg), &data->debug_mode))
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("could not parse value \"%s\" for parameter \"%s\"",
strVal(elem->arg), elem->defname)));
if (data->debug_mode)
opt->output_type = OUTPUT_PLUGIN_TEXTUAL_OUTPUT;
} else {
ereport(ERROR, (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("option \"%s\" = \"%s\" is unknown", elem->defname,
elem->arg ? strVal(elem->arg) : "(null)")));
}
}
}
/* cleanup this plugin's resources */
static void pg_decode_shutdown(LogicalDecodingContext *ctx) {
DecoderData *data = ctx->output_plugin_private;
/* cleanup our own resources via memory context reset */
MemoryContextDelete(data->context);
}
/* BEGIN callback */
static void pg_decode_begin_txn(LogicalDecodingContext *ctx,
ReorderBufferTXN *txn) {
}
/* COMMIT callback */
static void pg_decode_commit_txn(LogicalDecodingContext *ctx,
ReorderBufferTXN *txn, XLogRecPtr commit_lsn) {
}
/* convenience method to free up sub-messages */
static void free_row_msg_subs(Decoderbufs__RowMessage *msg) {
if (!msg) {
return;
}
pfree(msg->table);
if (msg->n_new_tuple > 0) {
for (int i = 0; i < msg->n_new_tuple; i++) {
if (msg->new_tuple[i]) {
if (msg->new_tuple[i]->datum_string) {
pfree(msg->new_tuple[i]->datum_string);
} else if (msg->new_tuple[i]->has_datum_bytes) {
pfree(msg->new_tuple[i]->datum_bytes.data);
msg->new_tuple[i]->datum_bytes.data = NULL;
msg->new_tuple[i]->datum_bytes.len = 0;
}
pfree(msg->new_tuple[i]);
}
}
pfree(msg->new_tuple);
}
if (msg->n_old_tuple > 0) {
for (int i = 0; i < msg->n_old_tuple; i++) {
if (msg->old_tuple[i]) {
if (msg->old_tuple[i]->datum_string) {
pfree(msg->old_tuple[i]->datum_string);
} else if (msg->old_tuple[i]->has_datum_bytes) {
pfree(msg->old_tuple[i]->datum_bytes.data);
msg->old_tuple[i]->datum_bytes.data = NULL;
msg->old_tuple[i]->datum_bytes.len = 0;
}
pfree(msg->old_tuple[i]);
}
}
pfree(msg->old_tuple);
}
}
/* only used for debug-mode (currently not all OIDs are currently supported) */
static void print_tuple_msg(StringInfo out, Decoderbufs__DatumMessage **tup,
size_t n) {
if (tup) {
for (int i = 0; i < n; i++) {
Decoderbufs__DatumMessage *dmsg = tup[i];
if (dmsg->column_name)
appendStringInfo(out, "column_name[%s]", dmsg->column_name);
if (dmsg->has_column_type) {
appendStringInfo(out, ", column_type[%" PRId64 "]", dmsg->column_type);
switch (dmsg->column_type) {
case INT2OID:
case INT4OID:
appendStringInfo(out, ", datum[%d]", dmsg->datum_int32);
break;
case INT8OID:
appendStringInfo(out, ", datum[%" PRId64 "]", dmsg->datum_int64);
break;
case FLOAT4OID:
appendStringInfo(out, ", datum[%f]", dmsg->datum_float);
break;
case FLOAT8OID:
case NUMERICOID:
appendStringInfo(out, ", datum[%f]", dmsg->datum_double);
break;
case TEXTOID:
case TIMESTAMPOID:
case TIMESTAMPTZOID:
appendStringInfo(out, ", datum[%s]", dmsg->datum_string);
break;
default:
break;
}
appendStringInfo(out, "\n");
}
}
}
}
/* this doesn't seem to be available in the public api (unfortunate) */
static double numeric_to_double_no_overflow(Numeric num) {
char *tmp;
double val;
char *endptr;
tmp = DatumGetCString(DirectFunctionCall1(numeric_out, NumericGetDatum(num)));
/* unlike float8in, we ignore ERANGE from strtod */
val = strtod(tmp, &endptr);
if (*endptr != '\0') {
/* shouldn't happen ... */
ereport(ERROR,
(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
errmsg("invalid input syntax for type double precision: \"%s\"",
tmp)));
}
pfree(tmp);
return val;
}
/* set a datum value based on its OID specified by typid */
static void set_datum_value(Decoderbufs__DatumMessage *datum_msg, Oid typid,
Oid typoutput, Datum datum) {
Numeric num;
bytea *valptr;
char *output;
switch (typid) {
case BOOLOID:
datum_msg->datum_bool = DatumGetBool(datum);
datum_msg->has_datum_bool = true;
break;
case INT2OID:
datum_msg->datum_int32 = DatumGetInt16(datum);
datum_msg->has_datum_int32 = true;
break;
case INT4OID:
datum_msg->datum_int32 = DatumGetInt32(datum);
datum_msg->has_datum_int32 = true;
break;
case INT8OID:
case OIDOID:
datum_msg->datum_int64 = DatumGetInt64(datum);
datum_msg->has_datum_int64 = true;
break;
case FLOAT4OID:
datum_msg->datum_float = DatumGetFloat4(datum);
datum_msg->has_datum_float = true;
break;
case FLOAT8OID:
datum_msg->datum_double = DatumGetFloat8(datum);
datum_msg->has_datum_double = true;
break;
case NUMERICOID:
num = DatumGetNumeric(datum);
if (!numeric_is_nan(num)) {
datum_msg->datum_double = numeric_to_double_no_overflow(num);
datum_msg->has_datum_double = true;
}
break;
case CHAROID:
case VARCHAROID:
case BPCHAROID:
case TEXTOID:
case JSONOID:
case XMLOID:
output = OidOutputFunctionCall(typoutput, datum);
datum_msg->datum_string = pnstrdup(output, strlen(output));
break;
case TIMESTAMPOID:
case TIMESTAMPTZOID:
datum_msg->datum_string = pstrdup(timestamptz_to_str(DatumGetTimestampTz(datum)));
break;
case BYTEAOID:
valptr = DatumGetByteaPCopy(datum);
int size = VARSIZE(valptr);
datum_msg->datum_bytes =
*((ProtobufCBinaryData *)palloc(sizeof(ProtobufCBinaryData)));
datum_msg->datum_bytes.data = (uint8_t *)VARDATA(valptr);
datum_msg->datum_bytes.len = size - VARHDRSZ;
datum_msg->has_datum_bytes = true;
break;
default:
output = OidOutputFunctionCall(typoutput, datum);
datum_msg->datum_bytes =
*((ProtobufCBinaryData *)palloc(sizeof(ProtobufCBinaryData)));
datum_msg->datum_bytes.data = (uint8_t *)output;
datum_msg->datum_bytes.len = sizeof(output);
datum_msg->has_datum_bytes = true;
break;
}
}
/* convert a PG tuple to an array of DatumMessage(s) */
static void tuple_to_tuple_msg(Decoderbufs__DatumMessage **tmsg,
Relation relation, HeapTuple tuple,
TupleDesc tupdesc) {
int natt;
/* build column names and values */
for (natt = 0; natt < tupdesc->natts; natt++) {
Form_pg_attribute attr;
Datum origval;
bool isnull;
attr = tupdesc->attrs[natt];
/* skip dropped columns and system columns */
if (attr->attisdropped || attr->attnum < 0) {
continue;
}
Decoderbufs__DatumMessage datum_msg = DECODERBUFS__DATUM_MESSAGE__INIT;
/* set the column name */
const char *col_name = quote_identifier(NameStr(attr->attname));
datum_msg.column_name = col_name;
/* set datum from tuple */
origval = fastgetattr(tuple, natt + 1, tupdesc, &isnull);
/* get output function */
datum_msg.column_type = attr->atttypid;
datum_msg.has_column_type = true;
Oid typoutput;
bool typisvarlena;
/* query output function */
getTypeOutputInfo(attr->atttypid, &typoutput, &typisvarlena);
if (!isnull) {
if (typisvarlena && VARATT_IS_EXTERNAL_ONDISK(origval)) {
// TODO: Is there a way we can handle this?
elog(WARNING, "Not handling external on disk varlena at the moment.");
} else if (!typisvarlena) {
set_datum_value(&datum_msg, attr->atttypid, typoutput, origval);
} else {
Datum val = PointerGetDatum(PG_DETOAST_DATUM(origval));
set_datum_value(&datum_msg, attr->atttypid, typoutput, val);
}
}
tmsg[natt] = palloc(sizeof(datum_msg));
memcpy(tmsg[natt], &datum_msg, sizeof(datum_msg));
}
}
/* callback for individual changed tuples */
static void pg_decode_change(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
Relation relation, ReorderBufferChange *change) {
DecoderData *data;
MemoryContext old;
Form_pg_class class_form;
char replident = relation->rd_rel->relreplident;
bool is_rel_non_selective;
Decoderbufs__RowMessage rmsg = DECODERBUFS__ROW_MESSAGE__INIT;
class_form = RelationGetForm(relation);
data = ctx->output_plugin_private;
/* Avoid leaking memory by using and resetting our own context */
old = MemoryContextSwitchTo(data->context);
RelationGetIndexList(relation);
is_rel_non_selective = (replident == REPLICA_IDENTITY_NOTHING ||
(replident == REPLICA_IDENTITY_DEFAULT &&
!OidIsValid(relation->rd_replidindex)));
/* set common fields */
rmsg.commit_time = TIMESTAMPTZ_TO_USEC_SINCE_EPOCH(txn->commit_time);
rmsg.has_commit_time = true;
rmsg.table = quote_qualified_identifier(
get_namespace_name(get_rel_namespace(RelationGetRelid(relation))),
NameStr(class_form->relname));
/* decode different operation types */
switch (change->action) {
case REORDER_BUFFER_CHANGE_INSERT:
rmsg.op = DECODERBUFS__OP__INSERT;
rmsg.has_op = true;
if (change->data.tp.newtuple != NULL) {
TupleDesc tupdesc = RelationGetDescr(relation);
rmsg.n_new_tuple = tupdesc->natts;
rmsg.new_tuple =
palloc(sizeof(Decoderbufs__DatumMessage) * tupdesc->natts);
tuple_to_tuple_msg(rmsg.new_tuple, relation,
&change->data.tp.newtuple->tuple, tupdesc);
}
break;
case REORDER_BUFFER_CHANGE_UPDATE:
rmsg.op = DECODERBUFS__OP__UPDATE;
rmsg.has_op = true;
if (!is_rel_non_selective) {
if (change->data.tp.oldtuple != NULL) {
TupleDesc tupdesc = RelationGetDescr(relation);
rmsg.n_old_tuple = tupdesc->natts;
rmsg.old_tuple =
palloc(sizeof(Decoderbufs__DatumMessage) * tupdesc->natts);
tuple_to_tuple_msg(rmsg.old_tuple, relation,
&change->data.tp.oldtuple->tuple, tupdesc);
}
if (change->data.tp.newtuple != NULL) {
TupleDesc tupdesc = RelationGetDescr(relation);
rmsg.n_new_tuple = tupdesc->natts;
rmsg.new_tuple =
palloc(sizeof(Decoderbufs__DatumMessage) * tupdesc->natts);
tuple_to_tuple_msg(rmsg.new_tuple, relation,
&change->data.tp.newtuple->tuple, tupdesc);
}
}
break;
case REORDER_BUFFER_CHANGE_DELETE:
rmsg.op = DECODERBUFS__OP__DELETE;
rmsg.has_op = true;
/* if there was no PK, we only know that a delete happened */
if (!is_rel_non_selective && change->data.tp.oldtuple != NULL) {
TupleDesc tupdesc = RelationGetDescr(relation);
rmsg.n_old_tuple = tupdesc->natts;
rmsg.old_tuple =
palloc(sizeof(Decoderbufs__DatumMessage) * tupdesc->natts);
tuple_to_tuple_msg(rmsg.old_tuple, relation,
&change->data.tp.oldtuple->tuple, tupdesc);
}
break;
default:
Assert(0);
break;
}
if (data->debug_mode) {
OutputPluginPrepareWrite(ctx, true);
if (rmsg.has_commit_time)
appendStringInfo(ctx->out, "commit_time[%" PRId64 "]", rmsg.commit_time);
if (rmsg.table)
appendStringInfo(ctx->out, ", table[%s]", rmsg.table);
if (rmsg.has_op)
appendStringInfo(ctx->out, ", op[%d]", rmsg.op);
if (rmsg.old_tuple) {
appendStringInfo(ctx->out, "\nOLD TUPLE: \n");
print_tuple_msg(ctx->out, rmsg.old_tuple, rmsg.n_old_tuple);
appendStringInfo(ctx->out, "\n");
}
if (rmsg.new_tuple) {
appendStringInfo(ctx->out, "\nNEW TUPLE: \n");
print_tuple_msg(ctx->out, rmsg.new_tuple, rmsg.n_new_tuple);
appendStringInfo(ctx->out, "\n");
}
OutputPluginWrite(ctx, true);
} else {
OutputPluginPrepareWrite(ctx, true);
size_t psize = decoderbufs__row_message__get_packed_size(&rmsg);
void *packed = palloc(psize);
size_t ssize = decoderbufs__row_message__pack(&rmsg, packed);
// appendBinaryStringInfo(ctx->out, (void *)psize, sizeof(psize));
appendBinaryStringInfo(ctx->out, packed, ssize);
OutputPluginWrite(ctx, true);
/* free packed buffer */
pfree(packed);
}
/* cleanup msg */
free_row_msg_subs(&rmsg);
MemoryContextSwitchTo(old);
MemoryContextReset(data->context);
}
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