From 9f1ca6ce6596f1f77adc323769f2f8303ddad14f Mon Sep 17 00:00:00 2001 From: David Rowley Date: Fri, 20 Jan 2023 13:07:24 +1300 Subject: [PATCH] Use appendStringInfoSpaces in more places This adjusts a few places which were appending a string constant containing spaces onto a StringInfo. We have appendStringInfoSpaces for that job, so let's use that instead. For the change to jsonb.c's add_indent() function, appendStringInfoString was being called inside a loop to append 4 spaces on each loop. This meant that enlargeStringInfo would get called once per loop. Here it should be much more efficient to get rid of the loop and just calculate the number of spaces with "level * 4" and just append all the spaces in one go. Here we additionally adjust the appendStringInfoSpaces function so it makes use of memset rather than a while loop to apply the required spaces to the StringInfo. One of the problems with the while loop was that it was incrementing one variable and decrementing another variable once per loop. That's more work than what's required to get the job done. We may as well use memset for this rather than trying to optimize the existing loop. Some testing has shown memset is faster even for very small sizes. Discussion: https://postgr.es/m/CAApHDvp_rKkvwudBKgBHniNRg67bzXVjyvVKfX0G2zS967K43A@mail.gmail.com --- src/backend/commands/explain.c | 2 +- src/backend/utils/adt/jsonb.c | 5 +---- src/common/stringinfo.c | 4 ++-- 3 files changed, 4 insertions(+), 7 deletions(-) diff --git a/src/backend/commands/explain.c b/src/backend/commands/explain.c index e4621ef8d6..5212a64b1e 100644 --- a/src/backend/commands/explain.c +++ b/src/backend/commands/explain.c @@ -3324,7 +3324,7 @@ show_hashagg_info(AggState *aggstate, ExplainState *es) if (!gotone) ExplainIndentText(es); else - appendStringInfoString(es->str, " "); + appendStringInfoSpaces(es->str, 2); appendStringInfo(es->str, "Batches: %d Memory Usage: " INT64_FORMAT "kB", aggstate->hash_batches_used, memPeakKb); diff --git a/src/backend/utils/adt/jsonb.c b/src/backend/utils/adt/jsonb.c index 4ff2eced4c..0539f41c17 100644 --- a/src/backend/utils/adt/jsonb.c +++ b/src/backend/utils/adt/jsonb.c @@ -626,11 +626,8 @@ add_indent(StringInfo out, bool indent, int level) { if (indent) { - int i; - appendStringInfoCharMacro(out, '\n'); - for (i = 0; i < level; i++) - appendBinaryStringInfo(out, " ", 4); + appendStringInfoSpaces(out, level * 4); } } diff --git a/src/common/stringinfo.c b/src/common/stringinfo.c index b3d3c99b8c..05b22b5c53 100644 --- a/src/common/stringinfo.c +++ b/src/common/stringinfo.c @@ -211,8 +211,8 @@ appendStringInfoSpaces(StringInfo str, int count) enlargeStringInfo(str, count); /* OK, append the spaces */ - while (--count >= 0) - str->data[str->len++] = ' '; + memset(&str->data[str->len], ' ', count); + str->len += count; str->data[str->len] = '\0'; } }