tags-fnode-cache: skip building a changectx in getfnode
Building a changectx object is costly, doing it just to retrieve the revision
number is suboptimal. Directly fetching the revision number from the changelog
provide a sizeable speedup to `hg debugupdatecache`.
### data-env-vars.name = mercurial-2018-08-01-zstd-sparse-revlog
# benchmark.name = debug-update-cache
# benchmark.variants.pre-state = warm
before: 0.213229 seconds
after: 0.165577 seconds (-22.35%)
# data-env-vars.name = mercurial-filtered-2019-11-22-zstd-sparse-revlog
before: 1.200383 seconds
after: 1.071618 seconds (-10.73%)
# data-env-vars.name = mozilla-central-2018-08-01-zstd-sparse-revlog
before: 1.465735 seconds
after: 0.923128 seconds (-37.02%)
# data-env-vars.name = mozilla-try-2019-02-18-zstd-sparse-revlog
before: 6.511771 seconds
after: 4.507316 seconds (-30.78%)
# data-env-vars.name = netbeans-2018-08-01-zstd-sparse-revlog
before: 1.023007 seconds
after: 0.645026 seconds (-36.95%)
# data-env-vars.name = pypy-2018-08-01-zstd-sparse-revlog
before: 0.381141 seconds
after: 0.268654 seconds (-29.51%)
TARGET = chg
SRCS = chg.c hgclient.c procutil.c util.c
OBJS = $(SRCS:.c=.o)
CFLAGS ?= -O2 -Wall -Wextra -pedantic -g
CPPFLAGS ?= -D_FORTIFY_SOURCE=2 -D_GNU_SOURCE
override CFLAGS += -std=gnu99
ifdef HGPATH
override CPPFLAGS += -DHGPATH=\"$(HGPATH)\"
endif
ifdef HGPATHREL
override CPPFLAGS += -DHGPATHREL=\"$(HGPATHREL)\"
endif
DESTDIR =
PREFIX = /usr/local
MANDIR = $(PREFIX)/share/man/man1
.PHONY: all
all: $(TARGET)
$(TARGET): $(OBJS)
$(CC) $(LDFLAGS) -o $@ $(OBJS)
chg.o: hgclient.h procutil.h util.h
hgclient.o: hgclient.h procutil.h util.h
procutil.o: procutil.h util.h
util.o: util.h
.PHONY: install
install: $(TARGET)
install -d "$(DESTDIR)$(PREFIX)"/bin
install -m 755 "$(TARGET)" "$(DESTDIR)$(PREFIX)"/bin
install -d "$(DESTDIR)$(MANDIR)"
install -m 644 chg.1 "$(DESTDIR)$(MANDIR)"
.PHONY: clean
clean:
$(RM) $(OBJS)
.PHONY: distclean
distclean:
$(RM) $(OBJS) $(TARGET)