On Fri, 30 Oct 2020 at 09:16, Amit Kapila <amit.kapil...@gmail.com> wrote
>
> 1.
> + LOGICAL_REP_MSG_STREAM_ABORT = 'A',
> +} LogicalRepMsgType;
>
> There is no need for a comma after the last message.
>
> Done. Thanks for noticing it.
> 2.
> +/*
> + * Logical message types
> + *
> + * Used by logical replication wire protocol.
> + *
> + * Note: though this is an enum it should fit a single byte and should be
> a
> + * printable character.
> + */
> +typedef enum
> +{
>
> I think we can expand the comments to probably say why we need these
> to fit in a single byte or what problem it can cause if that rule is
> disobeyed. This is to make the next person clear why we are imposing
> such a rule.
>
Done. Please check.
>
> 3.
> +typedef enum
> +{
> ..
> +} LogicalRepMsgType;
>
> There are places in code where we use the enum name
> (LogicalRepMsgType) both in the start and end. See TypeCat,
> CoercionMethod, CoercionCodes, etc. I see places where we use the way
> you have in the code. I would prefer the way we have used at places
> like TypeCat as that makes it easier to read.
>
Not my favourite style since changing the type name requires changing enum
name to keep those consistent. But anyway done.
>
> 4.
> switch (action)
> {
> - /* BEGIN */
> - case 'B':
> + case LOGICAL_REP_MSG_BEGIN:
> apply_handle_begin(s);
> - break;
> - /* COMMIT */
> - case 'C':
> + return;
>
> I think we can simply use 'return apply_handle_begin;' instead of
> adding return in another line. Again, I think we changed this handling
> in apply_dispatch() to improve the case where we can detect at the
> compile time any missing enum but at this stage it is not clear to me
> if that is true.
>
I don't see much value in writing it like "return apply_handle_begin()";
gives an impression that apply_handle_begin() and apply_dispatch() are
returning something which they are not. I would prefer return on separate
line unless there's something more than style improvement.
I have added rationale behind Enum in the commit message as you suggested
in one of the later mails.
PFA patch addressing your comments.
--
Best Wishes,
Ashutosh
From f71a600d3fd49756926deec1b593472a9fd8a8cc Mon Sep 17 00:00:00 2001
From: Ashutosh Bapat <ashutosh.ba...@2ndquadrant.com>
Date: Fri, 16 Oct 2020 12:31:35 +0530
Subject: [PATCH] Enumize top level logical replication actions
Logical replication protocol uses single byte character to identify a
message type in logical repliation protocol. The code uses string
literals for the same. Enumize those so that
1. All the string literals used can be found at a single place. This
makes it easy to add more types without the risk of conflicts.
2. It's easy to locate the code handling a given type.
3. When used with switch statements, it is easy to identify the missing
cases using -Wswitch.
Ashutosh Bapat
---
src/backend/replication/logical/proto.c | 26 +++----
src/backend/replication/logical/worker.c | 87 ++++++++++++------------
src/include/replication/logicalproto.h | 27 ++++++++
3 files changed, 83 insertions(+), 57 deletions(-)
diff --git a/src/backend/replication/logical/proto.c b/src/backend/replication/logical/proto.c
index eb19142b48..fdb31182d7 100644
--- a/src/backend/replication/logical/proto.c
+++ b/src/backend/replication/logical/proto.c
@@ -44,7 +44,7 @@ static const char *logicalrep_read_namespace(StringInfo in);
void
logicalrep_write_begin(StringInfo out, ReorderBufferTXN *txn)
{
- pq_sendbyte(out, 'B'); /* BEGIN */
+ pq_sendbyte(out, LOGICAL_REP_MSG_BEGIN);
/* fixed fields */
pq_sendint64(out, txn->final_lsn);
@@ -76,7 +76,7 @@ logicalrep_write_commit(StringInfo out, ReorderBufferTXN *txn,
{
uint8 flags = 0;
- pq_sendbyte(out, 'C'); /* sending COMMIT */
+ pq_sendbyte(out, LOGICAL_REP_MSG_COMMIT);
/* send the flags field (unused for now) */
pq_sendbyte(out, flags);
@@ -112,7 +112,7 @@ void
logicalrep_write_origin(StringInfo out, const char *origin,
XLogRecPtr origin_lsn)
{
- pq_sendbyte(out, 'O'); /* ORIGIN */
+ pq_sendbyte(out, LOGICAL_REP_MSG_ORIGIN);
/* fixed fields */
pq_sendint64(out, origin_lsn);
@@ -141,7 +141,7 @@ void
logicalrep_write_insert(StringInfo out, TransactionId xid, Relation rel,
HeapTuple newtuple, bool binary)
{
- pq_sendbyte(out, 'I'); /* action INSERT */
+ pq_sendbyte(out, LOGICAL_REP_MSG_INSERT);
/* transaction ID (if not valid, we're not streaming) */
if (TransactionIdIsValid(xid))
@@ -185,7 +185,7 @@ void
logicalrep_write_update(StringInfo out, TransactionId xid, Relation rel,
HeapTuple oldtuple, HeapTuple newtuple, bool binary)
{
- pq_sendbyte(out, 'U'); /* action UPDATE */
+ pq_sendbyte(out, LOGICAL_REP_MSG_UPDATE);
Assert(rel->rd_rel->relreplident == REPLICA_IDENTITY_DEFAULT ||
rel->rd_rel->relreplident == REPLICA_IDENTITY_FULL ||
@@ -263,7 +263,7 @@ logicalrep_write_delete(StringInfo out, TransactionId xid, Relation rel,
rel->rd_rel->relreplident == REPLICA_IDENTITY_FULL ||
rel->rd_rel->relreplident == REPLICA_IDENTITY_INDEX);
- pq_sendbyte(out, 'D'); /* action DELETE */
+ pq_sendbyte(out, LOGICAL_REP_MSG_DELETE);
/* transaction ID (if not valid, we're not streaming) */
if (TransactionIdIsValid(xid))
@@ -317,7 +317,7 @@ logicalrep_write_truncate(StringInfo out,
int i;
uint8 flags = 0;
- pq_sendbyte(out, 'T'); /* action TRUNCATE */
+ pq_sendbyte(out, LOGICAL_REP_MSG_TRUNCATE);
/* transaction ID (if not valid, we're not streaming) */
if (TransactionIdIsValid(xid))
@@ -369,7 +369,7 @@ logicalrep_write_rel(StringInfo out, TransactionId xid, Relation rel)
{
char *relname;
- pq_sendbyte(out, 'R'); /* sending RELATION */
+ pq_sendbyte(out, LOGICAL_REP_MSG_RELATION);
/* transaction ID (if not valid, we're not streaming) */
if (TransactionIdIsValid(xid))
@@ -425,7 +425,7 @@ logicalrep_write_typ(StringInfo out, TransactionId xid, Oid typoid)
HeapTuple tup;
Form_pg_type typtup;
- pq_sendbyte(out, 'Y'); /* sending TYPE */
+ pq_sendbyte(out, LOGICAL_REP_MSG_TYPE);
/* transaction ID (if not valid, we're not streaming) */
if (TransactionIdIsValid(xid))
@@ -755,7 +755,7 @@ void
logicalrep_write_stream_start(StringInfo out,
TransactionId xid, bool first_segment)
{
- pq_sendbyte(out, 'S'); /* action STREAM START */
+ pq_sendbyte(out, LOGICAL_REP_MSG_STREAM_START);
Assert(TransactionIdIsValid(xid));
@@ -788,7 +788,7 @@ logicalrep_read_stream_start(StringInfo in, bool *first_segment)
void
logicalrep_write_stream_stop(StringInfo out)
{
- pq_sendbyte(out, 'E'); /* action STREAM END */
+ pq_sendbyte(out, LOGICAL_REP_MSG_STREAM_END);
}
/*
@@ -800,7 +800,7 @@ logicalrep_write_stream_commit(StringInfo out, ReorderBufferTXN *txn,
{
uint8 flags = 0;
- pq_sendbyte(out, 'c'); /* action STREAM COMMIT */
+ pq_sendbyte(out, LOGICAL_REP_MSG_STREAM_COMMIT);
Assert(TransactionIdIsValid(txn->xid));
@@ -849,7 +849,7 @@ void
logicalrep_write_stream_abort(StringInfo out, TransactionId xid,
TransactionId subxid)
{
- pq_sendbyte(out, 'A'); /* action STREAM ABORT */
+ pq_sendbyte(out, LOGICAL_REP_MSG_STREAM_ABORT);
Assert(TransactionIdIsValid(xid) && TransactionIdIsValid(subxid));
diff --git a/src/backend/replication/logical/worker.c b/src/backend/replication/logical/worker.c
index b0f27e0af8..04684912de 100644
--- a/src/backend/replication/logical/worker.c
+++ b/src/backend/replication/logical/worker.c
@@ -1896,67 +1896,66 @@ apply_handle_truncate(StringInfo s)
static void
apply_dispatch(StringInfo s)
{
- char action = pq_getmsgbyte(s);
+ LogicalRepMsgType action = pq_getmsgbyte(s);
switch (action)
{
- /* BEGIN */
- case 'B':
+ case LOGICAL_REP_MSG_BEGIN:
apply_handle_begin(s);
- break;
- /* COMMIT */
- case 'C':
+ return;
+
+ case LOGICAL_REP_MSG_COMMIT:
apply_handle_commit(s);
- break;
- /* INSERT */
- case 'I':
+ return;
+
+ case LOGICAL_REP_MSG_INSERT:
apply_handle_insert(s);
- break;
- /* UPDATE */
- case 'U':
+ return;
+
+ case LOGICAL_REP_MSG_UPDATE:
apply_handle_update(s);
- break;
- /* DELETE */
- case 'D':
+ return;
+
+ case LOGICAL_REP_MSG_DELETE:
apply_handle_delete(s);
- break;
- /* TRUNCATE */
- case 'T':
+ return;
+
+ case LOGICAL_REP_MSG_TRUNCATE:
apply_handle_truncate(s);
- break;
- /* RELATION */
- case 'R':
+ return;
+
+ case LOGICAL_REP_MSG_RELATION:
apply_handle_relation(s);
- break;
- /* TYPE */
- case 'Y':
+ return;
+
+ case LOGICAL_REP_MSG_TYPE:
apply_handle_type(s);
- break;
- /* ORIGIN */
- case 'O':
+ return;
+
+ case LOGICAL_REP_MSG_ORIGIN:
apply_handle_origin(s);
- break;
- /* STREAM START */
- case 'S':
+ return;
+
+ case LOGICAL_REP_MSG_STREAM_START:
apply_handle_stream_start(s);
- break;
- /* STREAM END */
- case 'E':
+ return;
+
+ case LOGICAL_REP_MSG_STREAM_END:
apply_handle_stream_stop(s);
- break;
- /* STREAM ABORT */
- case 'A':
+ return;
+
+ case LOGICAL_REP_MSG_STREAM_ABORT:
apply_handle_stream_abort(s);
- break;
- /* STREAM COMMIT */
- case 'c':
+ return;
+
+ case LOGICAL_REP_MSG_STREAM_COMMIT:
apply_handle_stream_commit(s);
- break;
- default:
- ereport(ERROR,
- (errcode(ERRCODE_PROTOCOL_VIOLATION),
- errmsg("invalid logical replication message type \"%c\"", action)));
+ return;
}
+
+ ereport(ERROR,
+ (errcode(ERRCODE_PROTOCOL_VIOLATION),
+ errmsg("invalid logical replication message type \"%c\"", action)));
}
/*
diff --git a/src/include/replication/logicalproto.h b/src/include/replication/logicalproto.h
index 0c2cda264e..cca13dae96 100644
--- a/src/include/replication/logicalproto.h
+++ b/src/include/replication/logicalproto.h
@@ -33,6 +33,33 @@
#define LOGICALREP_PROTO_STREAM_VERSION_NUM 2
#define LOGICALREP_PROTO_MAX_VERSION_NUM LOGICALREP_PROTO_STREAM_VERSION_NUM
+/*
+ * Logical message types
+ *
+ * Used by logical replication wire protocol.
+ *
+ * Note: though this is an enum, the values are used to identify message types
+ * in logical replication protocol, which uses a single byte to identify a
+ * message type. Hence the values should be single byte wide and preferrably
+ * human readable characters.
+ */
+typedef enum LogicalRepMsgType
+{
+ LOGICAL_REP_MSG_BEGIN = 'B',
+ LOGICAL_REP_MSG_COMMIT = 'C',
+ LOGICAL_REP_MSG_ORIGIN = 'O',
+ LOGICAL_REP_MSG_INSERT = 'I',
+ LOGICAL_REP_MSG_UPDATE = 'U',
+ LOGICAL_REP_MSG_DELETE = 'D',
+ LOGICAL_REP_MSG_TRUNCATE = 'T',
+ LOGICAL_REP_MSG_RELATION = 'R',
+ LOGICAL_REP_MSG_TYPE = 'Y',
+ LOGICAL_REP_MSG_STREAM_START = 'S',
+ LOGICAL_REP_MSG_STREAM_END = 'E',
+ LOGICAL_REP_MSG_STREAM_COMMIT = 'c',
+ LOGICAL_REP_MSG_STREAM_ABORT = 'A'
+} LogicalRepMsgType;
+
/*
* This struct stores a tuple received via logical replication.
* Keep in mind that the columns correspond to the *remote* table.
--
2.17.1
