Merge branch 'nd/threaded-index-pack'

Enables threading in index-pack to resolve base data in parallel.

By Nguyễn Thái Ngọc Duy (3) and Ramsay Jones (1)
* nd/threaded-index-pack:
  index-pack: disable threading if NO_PREAD is defined
  index-pack: support multithreaded delta resolving
  index-pack: restructure pack processing into three main functions
  compat/win32/pthread.h: Add an pthread_key_delete() implementation

t/perf/p5302-pack-index.sh

@@ -0,0 +1,40 @@
+#!/bin/sh
+
+test_description="Tests index-pack performance"
+
+. ./perf-lib.sh
+
+test_perf_large_repo
+
+test_expect_success 'repack' '
+	git repack -ad &&
+	PACK=`ls .git/objects/pack/*.pack | head -n1` &&
+	test -f "$PACK" &&
+	export PACK
+'
+
+test_perf 'index-pack 0 threads' '
+	GIT_DIR=t1 git index-pack --threads=1 --stdin < $PACK
+'
+
+test_perf 'index-pack 1 thread ' '
+	GIT_DIR=t2 GIT_FORCE_THREADS=1 git index-pack --threads=1 --stdin < $PACK
+'
+
+test_perf 'index-pack 2 threads' '
+	GIT_DIR=t3 git index-pack --threads=2 --stdin < $PACK
+'
+
+test_perf 'index-pack 4 threads' '
+	GIT_DIR=t4 git index-pack --threads=4 --stdin < $PACK
+'
+
+test_perf 'index-pack 8 threads' '
+	GIT_DIR=t5 git index-pack --threads=8 --stdin < $PACK
+'
+
+test_perf 'index-pack default number of threads' '
+	GIT_DIR=t6 git index-pack --stdin < $PACK
+'
+
+test_done