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Makefiles: add and use wildcard "mkdir -p" template
Add a template to do the "mkdir -p" of $(@d) (the parent dir of $@) for us, and use it for the "make lint-docs" targets I added in 8650c62 (doc lint: make "lint-docs" non-.PHONY, 2021-10-15). As seen in 4c64fb5 (Documentation/Makefile: fix lint-docs mkdir dependency, 2021-10-26) maintaining these manual lists of parent directory dependencies is fragile, in addition to being obviously verbose. I used this pattern at the time because I couldn't find another method than "order-only" prerequisites to avoid doing a "mkdir -p $(@d)" for every file being created, which as noted in [1] would be significantly slower. But as it turns out we can use this neat trick of only doing a "mkdir -p" if the $(wildcard) macro tells us the path doesn't exist. A re-run of a performance test similar to that noted downthread of [1] in [2] shows that this is faster, in addition to being less verbose and more reliable (this uses my "git-hyperfine" thin wrapper for "hyperfine"[3]): $ git -c hyperfine.hook.setup= hyperfine -L rev HEAD~1,HEAD~0 -s 'make -C Documentation lint-docs' -p 'rm -rf Documentation/.build' 'make -C Documentation -j1 lint-docs' Benchmark 1: make -C Documentation -j1 lint-docs' in 'HEAD~1 Time (mean ± σ): 2.914 s ± 0.062 s [User: 2.449 s, System: 0.489 s] Range (min … max): 2.834 s … 3.020 s 10 runs Benchmark 2: make -C Documentation -j1 lint-docs' in 'HEAD~0 Time (mean ± σ): 2.315 s ± 0.062 s [User: 1.950 s, System: 0.386 s] Range (min … max): 2.229 s … 2.397 s 10 runs Summary 'make -C Documentation -j1 lint-docs' in 'HEAD~0' ran 1.26 ± 0.04 times faster than 'make -C Documentation -j1 lint-docs' in 'HEAD~1' So let's use that pattern both for the "lint-docs" target, and a few miscellaneous other targets. This method of creating parent directories is explicitly racy in that we don't know if we're going to say always create a "foo" followed by a "foo/bar" under parallelism, or skip the "foo" because we created "foo/bar" first. In this case it doesn't matter for anything except that we aren't guaranteed to get the same number of rules firing when running make in parallel. 1. https://lore.kernel.org/git/211028.861r45y3pt.gmgdl@evledraar.gmail.com/ 2. https://lore.kernel.org/git/211028.86o879vvtp.gmgdl@evledraar.gmail.com/ 3. https://gitlab.com/avar/git-hyperfine/ Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
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‎Documentation/Makefile‎

Lines changed: 3 additions & 22 deletions
Original file line numberDiff line numberDiff line change
@@ -434,25 +434,11 @@ quick-install-html: require-htmlrepo
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print-man1:
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@for i in $(MAN1_TXT); do echo $$i; done
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## Lint: Common
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.build:
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$(QUIET)mkdir $@
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.build/lint-docs: | .build
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$(QUIET)mkdir $@
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## Lint: gitlink
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.build/lint-docs/gitlink: | .build/lint-docs
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$(QUIET)mkdir $@
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.build/lint-docs/gitlink/howto: | .build/lint-docs/gitlink
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$(QUIET)mkdir $@
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.build/lint-docs/gitlink/config: | .build/lint-docs/gitlink
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$(QUIET)mkdir $@
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LINT_DOCS_GITLINK = $(patsubst %.txt,.build/lint-docs/gitlink/%.ok,$(HOWTO_TXT) $(DOC_DEP_TXT))
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$(LINT_DOCS_GITLINK): | .build/lint-docs/gitlink
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$(LINT_DOCS_GITLINK): | .build/lint-docs/gitlink/howto
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$(LINT_DOCS_GITLINK): | .build/lint-docs/gitlink/config
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$(LINT_DOCS_GITLINK): lint-gitlink.perl
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$(LINT_DOCS_GITLINK): .build/lint-docs/gitlink/%.ok: %.txt
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$(call mkdir_p_parent_template)
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$(QUIET_LINT_GITLINK)$(PERL_PATH) lint-gitlink.perl \
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$< \
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$(HOWTO_TXT) $(DOC_DEP_TXT) \
@@ -463,23 +449,18 @@ $(LINT_DOCS_GITLINK): .build/lint-docs/gitlink/%.ok: %.txt
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lint-docs-gitlink: $(LINT_DOCS_GITLINK)
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## Lint: man-end-blurb
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.build/lint-docs/man-end-blurb: | .build/lint-docs
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$(QUIET)mkdir $@
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LINT_DOCS_MAN_END_BLURB = $(patsubst %.txt,.build/lint-docs/man-end-blurb/%.ok,$(MAN_TXT))
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$(LINT_DOCS_MAN_END_BLURB): | .build/lint-docs/man-end-blurb
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$(LINT_DOCS_MAN_END_BLURB): lint-man-end-blurb.perl
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$(LINT_DOCS_MAN_END_BLURB): .build/lint-docs/man-end-blurb/%.ok: %.txt
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$(call mkdir_p_parent_template)
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$(QUIET_LINT_MANEND)$(PERL_PATH) lint-man-end-blurb.perl $< >$@
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.PHONY: lint-docs-man-end-blurb
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lint-docs-man-end-blurb: $(LINT_DOCS_MAN_END_BLURB)
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## Lint: man-section-order
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.build/lint-docs/man-section-order: | .build/lint-docs
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$(QUIET)mkdir $@
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LINT_DOCS_MAN_SECTION_ORDER = $(patsubst %.txt,.build/lint-docs/man-section-order/%.ok,$(MAN_TXT))
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$(LINT_DOCS_MAN_SECTION_ORDER): | .build/lint-docs/man-section-order
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$(LINT_DOCS_MAN_SECTION_ORDER): lint-man-section-order.perl
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$(LINT_DOCS_MAN_SECTION_ORDER): .build/lint-docs/man-section-order/%.ok: %.txt
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$(call mkdir_p_parent_template)
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$(QUIET_LINT_MANSEC)$(PERL_PATH) lint-man-section-order.perl $< >$@
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.PHONY: lint-docs-man-section-order
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lint-docs-man-section-order: $(LINT_DOCS_MAN_SECTION_ORDER)

‎Makefile‎

Lines changed: 7 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -2745,7 +2745,8 @@ all:: $(MOFILES)
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endif
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po/build/locale/%/LC_MESSAGES/git.mo: po/%.po
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$(QUIET_MSGFMT)mkdir -p $(dir $@) && $(MSGFMT) -o $@ $<
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$(call mkdir_p_parent_template)
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$(QUIET_MSGFMT)$(MSGFMT) -o $@ $<
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LIB_PERL := $(wildcard perl/Git.pm perl/Git/*.pm perl/Git/*/*.pm perl/Git/*/*/*.pm)
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LIB_PERL_GEN := $(patsubst perl/%.pm,perl/build/lib/%.pm,$(LIB_PERL))
@@ -2761,15 +2762,16 @@ NO_PERL_CPAN_FALLBACKS_SQ = $(subst ','\'',$(NO_PERL_CPAN_FALLBACKS))
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endif
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perl/build/lib/%.pm: perl/%.pm GIT-PERL-DEFINES
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$(QUIET_GEN)mkdir -p $(dir $@) && \
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$(call mkdir_p_parent_template)
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$(QUIET_GEN) \
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sed -e 's|@@LOCALEDIR@@|$(perl_localedir_SQ)|g' \
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-e 's|@@NO_GETTEXT@@|$(NO_GETTEXT_SQ)|g' \
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-e 's|@@NO_PERL_CPAN_FALLBACKS@@|$(NO_PERL_CPAN_FALLBACKS_SQ)|g' \
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< $< > $@
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perl/build/man/man3/Git.3pm: perl/Git.pm
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$(QUIET_GEN)mkdir -p $(dir $@) && \
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pod2man $< $@
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$(call mkdir_p_parent_template)
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$(QUIET_GEN)pod2man $< $@
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$(ETAGS_TARGET): $(FOUND_SOURCE_FILES)
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$(QUIET_GEN)$(RM) $@+ && \
@@ -2903,7 +2905,7 @@ test_bindir_programs := $(patsubst %,bin-wrappers/%,$(BINDIR_PROGRAMS_NEED_X) $(
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all:: $(TEST_PROGRAMS) $(test_bindir_programs)
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29052907
bin-wrappers/%: wrap-for-bin.sh
2906-
@mkdir -p bin-wrappers
2908+
$(call mkdir_p_parent_template)
29072909
$(QUIET_GEN)sed -e '1s|#!.*/sh|#!$(SHELL_PATH_SQ)|' \
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-e 's|@@BUILD_DIR@@|$(shell pwd)|' \
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-e 's|@@PROG@@|$(patsubst test-%,t/helper/test-%$(X),$(@F))$(patsubst git%,$(X),$(filter $(@F),$(BINDIR_PROGRAMS_NEED_X)))|' < $< > $@ && \

‎shared.mak‎

Lines changed: 17 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -53,6 +53,8 @@ ifndef V
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QUIET = @
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QUIET_GEN = @echo ' ' GEN $@;
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QUIET_MKDIR_P_PARENT = @echo $(wspfx_SQ) MKDIR -p $(@D);
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## Used in "Makefile"
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QUIET_CC = @echo ' ' CC $@;
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QUIET_AR = @echo ' ' AR $@;
@@ -84,3 +86,18 @@ ifndef V
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export V
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endif
8688
endif
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### Templates
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## mkdir_p_parent: lazily "mkdir -p" the path needed for a $@
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## file. Uses $(wildcard) to avoid the "mkdir -p" if it's not
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## needed.
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##
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## Is racy, but in a good way; we might redundantly (and safely)
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## "mkdir -p" when running in parallel, but won't need to exhaustively create
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## individual rules for "a" -> "prefix" -> "dir" -> "file" if given a
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## "a/prefix/dir/file". This can instead be inserted at the start of
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## the "a/prefix/dir/file" rule.
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define mkdir_p_parent_template
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$(if $(wildcard $(@D)),,$(QUIET_MKDIR_P_PARENT)$(shell mkdir -p $(@D)))
103+
endef

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