Consistently declare timestamp variables as TimestampTz.

Twiddle the replication-related code so that its timestamp variables
are declared TimestampTz, rather than the uninformative "int64" that
was previously used for meant-to-be-always-integer timestamps.
This resolves the int64-vs-TimestampTz declaration inconsistencies
introduced by commit 7c030783a, though in the opposite direction to
what was originally suggested.

This required including datatype/timestamp.h in a couple more places
than before.  I decided it would be a good idea to slim down that
header by not having it pull in <float.h> etc, as those headers are
no longer at all relevant to its purpose.  Unsurprisingly, a small number
of .c files turn out to have been depending on those inclusions, so add
them back in the .c files as needed.

Discussion: https://postgr.es/m/26788.1487455319@sss.pgh.pa.us
Discussion: https://postgr.es/m/27694.1487456324@sss.pgh.pa.us

src/backend/replication/basebackup.c

@@ -92,10 +92,10 @@ static uint64 throttling_sample;
 static int64 throttling_counter;
 
 /* The minimum time required to transfer throttling_sample bytes. */
-static int64 elapsed_min_unit;
+static TimeOffset elapsed_min_unit;
 
 /* The last check of the transfer rate. */
-static int64 throttled_last;
+static TimestampTz throttled_last;
 
 /*
  * The contents of these directories are removed or recreated during server
@@ -254,7 +254,7 @@ perform_base_backup(basebackup_options *opt, DIR *tblspcdir)
 			throttling_counter = 0;
 
 			/* The 'real data' starts now (header was ignored). */
-			throttled_last = GetCurrentIntegerTimestamp();
+			throttled_last = GetCurrentTimestamp();
 		}
 		else
 		{
@@ -1333,7 +1333,7 @@ _tarWriteDir(const char *pathbuf, int basepathlen, struct stat *statbuf,
 static void
 throttle(size_t increment)
 {
-	int64		elapsed,
+	TimeOffset	elapsed,
 				elapsed_min,
 				sleep;
 	int			wait_result;
@@ -1346,7 +1346,7 @@ throttle(size_t increment)
 		return;
 
 	/* Time elapsed since the last measurement (and possible wake up). */
-	elapsed = GetCurrentIntegerTimestamp() - throttled_last;
+	elapsed = GetCurrentTimestamp() - throttled_last;
 	/* How much should have elapsed at minimum? */
 	elapsed_min = elapsed_min_unit * (throttling_counter / throttling_sample);
 	sleep = elapsed_min - elapsed;
@@ -1381,5 +1381,5 @@ throttle(size_t increment)
 	 * Time interval for the remaining amount and possible next increments
 	 * starts now.
 	 */
-	throttled_last = GetCurrentIntegerTimestamp();
+	throttled_last = GetCurrentTimestamp();
 }

src/backend/replication/logical/worker.c

@@ -981,12 +981,11 @@ ApplyLoop(void)
 					{
 						XLogRecPtr	start_lsn;
 						XLogRecPtr	end_lsn;
-						TimestampTz	send_time;
+						TimestampTz send_time;
 
 						start_lsn = pq_getmsgint64(&s);
 						end_lsn = pq_getmsgint64(&s);
-						send_time =
-							IntegerTimestampToTimestampTz(pq_getmsgint64(&s));
+						send_time = pq_getmsgint64(&s);
 
 						if (last_received < start_lsn)
 							last_received = start_lsn;
@@ -1000,13 +999,12 @@ ApplyLoop(void)
 					}
 					else if (c == 'k')
 					{
-						XLogRecPtr endpos;
-						TimestampTz	timestamp;
-						bool reply_requested;
+						XLogRecPtr	endpos;
+						TimestampTz timestamp;
+						bool		reply_requested;
 
 						endpos = pq_getmsgint64(&s);
-						timestamp =
-							IntegerTimestampToTimestampTz(pq_getmsgint64(&s));
+						timestamp = pq_getmsgint64(&s);
 						reply_requested = pq_getmsgbyte(&s);
 
 						send_feedback(endpos, reply_requested, false);

src/backend/replication/walreceiver.c

@@ -892,8 +892,7 @@ XLogWalRcvProcessMsg(unsigned char type, char *buf, Size len)
 				/* read the fields */
 				dataStart = pq_getmsgint64(&incoming_message);
 				walEnd = pq_getmsgint64(&incoming_message);
-				sendTime = IntegerTimestampToTimestampTz(
-										  pq_getmsgint64(&incoming_message));
+				sendTime = pq_getmsgint64(&incoming_message);
 				ProcessWalSndrMessage(walEnd, sendTime);
 
 				buf += hdrlen;
@@ -913,8 +912,7 @@ XLogWalRcvProcessMsg(unsigned char type, char *buf, Size len)
 
 				/* read the fields */
 				walEnd = pq_getmsgint64(&incoming_message);
-				sendTime = IntegerTimestampToTimestampTz(
-										  pq_getmsgint64(&incoming_message));
+				sendTime = pq_getmsgint64(&incoming_message);
 				replyRequested = pq_getmsgbyte(&incoming_message);
 
 				ProcessWalSndrMessage(walEnd, sendTime);
@@ -1149,7 +1147,7 @@ XLogWalRcvSendReply(bool force, bool requestReply)
 	pq_sendint64(&reply_message, writePtr);
 	pq_sendint64(&reply_message, flushPtr);
 	pq_sendint64(&reply_message, applyPtr);
-	pq_sendint64(&reply_message, GetCurrentIntegerTimestamp());
+	pq_sendint64(&reply_message, GetCurrentTimestamp());
 	pq_sendbyte(&reply_message, requestReply ? 1 : 0);
 
 	/* Send it */
@@ -1241,7 +1239,7 @@ XLogWalRcvSendHSFeedback(bool immed)
 	/* Construct the message and send it. */
 	resetStringInfo(&reply_message);
 	pq_sendbyte(&reply_message, 'h');
-	pq_sendint64(&reply_message, GetCurrentIntegerTimestamp());
+	pq_sendint64(&reply_message, GetCurrentTimestamp());
 	pq_sendint(&reply_message, xmin, 4);
 	pq_sendint(&reply_message, nextEpoch, 4);
 	walrcv_send(wrconn, reply_message.data, reply_message.len);

src/backend/replication/walsender.c

@@ -823,12 +823,13 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
 	dest = CreateDestReceiver(DestRemoteSimple);
 	MemSet(nulls, false, sizeof(nulls));
 
-	/*
+	/*----------
 	 * Need a tuple descriptor representing four columns:
 	 * - first field: the slot name
 	 * - second field: LSN at which we became consistent
 	 * - third field: exported snapshot's name
 	 * - fourth field: output plugin
+	 *----------
 	 */
 	tupdesc = CreateTemplateTupleDesc(4, false);
 	TupleDescInitBuiltinEntry(tupdesc, (AttrNumber) 1, "slot_name",
@@ -1014,7 +1015,7 @@ WalSndWriteData(LogicalDecodingContext *ctx, XLogRecPtr lsn, TransactionId xid,
 	 * several releases by streaming physical replication.
 	 */
 	resetStringInfo(&tmpbuf);
-	pq_sendint64(&tmpbuf, GetCurrentIntegerTimestamp());
+	pq_sendint64(&tmpbuf, GetCurrentTimestamp());
 	memcpy(&ctx->out->data[1 + sizeof(int64) + sizeof(int64)],
 		   tmpbuf.data, sizeof(int64));
 
@@ -2334,7 +2335,7 @@ XLogSendPhysical(void)
 	 * Fill the send timestamp last, so that it is taken as late as possible.
 	 */
 	resetStringInfo(&tmpbuf);
-	pq_sendint64(&tmpbuf, GetCurrentIntegerTimestamp());
+	pq_sendint64(&tmpbuf, GetCurrentTimestamp());
 	memcpy(&output_message.data[1 + sizeof(int64) + sizeof(int64)],
 		   tmpbuf.data, sizeof(int64));
 
@@ -2842,7 +2843,7 @@ WalSndKeepalive(bool requestReply)
 	resetStringInfo(&output_message);
 	pq_sendbyte(&output_message, 'k');
 	pq_sendint64(&output_message, sentPtr);
-	pq_sendint64(&output_message, GetCurrentIntegerTimestamp());
+	pq_sendint64(&output_message, GetCurrentTimestamp());
 	pq_sendbyte(&output_message, requestReply ? 1 : 0);
 
 	/* ... and send it wrapped in CopyData */