Refactor Copy{From|To}GetRoutine() to use pass-by-reference argument.

The change improves efficiency by eliminating unnecessary copying of
CopyFormatOptions.

The coverity also complained about inefficiencies caused by
pass-by-value.

Oversight in 7717f6300 and 2e4127b6d.

Reported-by: Junwang Zhao <zhjwpku@gmail.com>
Reported-by: Tom Lane <tgl@sss.pgh.pa.us> (per reports from coverity)
Author: Sutou Kouhei <kou@clear-code.com>
Reviewed-by: Junwang Zhao <zhjwpku@gmail.com>
Reviewed-by: Masahiko Sawada <sawada.mshk@gmail.com>
Discussion: https://postgr.es/m/CAEG8a3L6YCpPksTQMzjD_CvwDEhW3D_t=5md9BvvdOs5k+TA=Q@mail.gmail.com

src/backend/commands/copyfrom.c

@@ -153,11 +153,11 @@ static const CopyFromRoutine CopyFromRoutineBinary = {
 
 /* Return a COPY FROM routine for the given options */
 static const CopyFromRoutine *
-CopyFromGetRoutine(CopyFormatOptions opts)
+CopyFromGetRoutine(const CopyFormatOptions *opts)
 {
-	if (opts.csv_mode)
+	if (opts->csv_mode)
 		return &CopyFromRoutineCSV;
-	else if (opts.binary)
+	else if (opts->binary)
 		return &CopyFromRoutineBinary;
 
 	/* default is text */
@@ -1574,7 +1574,7 @@ BeginCopyFrom(ParseState *pstate,
 	ProcessCopyOptions(pstate, &cstate->opts, true /* is_from */ , options);
 
 	/* Set the format routine */
-	cstate->routine = CopyFromGetRoutine(cstate->opts);
+	cstate->routine = CopyFromGetRoutine(&cstate->opts);
 
 	/* Process the target relation */
 	cstate->rel = rel;

src/backend/commands/copyto.c

@@ -174,11 +174,11 @@ static const CopyToRoutine CopyToRoutineBinary = {
 
 /* Return a COPY TO routine for the given options */
 static const CopyToRoutine *
-CopyToGetRoutine(CopyFormatOptions opts)
+CopyToGetRoutine(const CopyFormatOptions *opts)
 {
-	if (opts.csv_mode)
+	if (opts->csv_mode)
 		return &CopyToRoutineCSV;
-	else if (opts.binary)
+	else if (opts->binary)
 		return &CopyToRoutineBinary;
 
 	/* default is text */
@@ -700,7 +700,7 @@ BeginCopyTo(ParseState *pstate,
 	ProcessCopyOptions(pstate, &cstate->opts, false /* is_from */ , options);
 
 	/* Set format routine */
-	cstate->routine = CopyToGetRoutine(cstate->opts);
+	cstate->routine = CopyToGetRoutine(&cstate->opts);
 
 	/* Process the source/target relation or query */
 	if (rel)