view contrib/chg/Makefile @ 47120:7109a38830c9

dirstate-tree: Fold "tracked descendants" counter update in main walk

For the purpose of implementing `has_tracked_dir` (which means "has tracked
descendants) without an expensive sub-tree traversal, we maintaing a counter
of tracked descendants on each "directory" node of the tree-shaped dirstate.

Before this changeset, mutating or inserting a node at a given path would
involve:

* Walking the tree from root through ancestors to find the node or the spot
  where to insert it
* Looking at the previous node if any to decide what counter update is needed
* Performing any node mutation
* Walking the tree *again* to update counters in ancestor nodes

When profiling `hg status` on a large repo, this second walk takes times
while loading a the dirstate from disk.

It turns out we have enough information to decide before he first tree walk
what counter update is needed. This changeset merges the two walks, gaining
~10% of the total time for `hg update` (in the same hyperfine benchmark as
the previous changeset).

---

Profiling was done by compiling with this `.cargo/config`:

    [profile.release]
    debug = true

then running with:

    py-spy record -r 500 -n -o /tmp/hg.json --format speedscope -- \
    ./hg status -R $REPO --config experimental.dirstate-tree.in-memory=1

then visualizing the recorded JSON file in https://www.speedscope.app/

Differential Revision: https://phab.mercurial-scm.org/D10554

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)