view contrib/chg/hgclient.h @ 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

/*
 * A command server client that uses Unix domain socket
 *
 * Copyright (c) 2011 Yuya Nishihara <[e-mail]>
 *
 * This software may be used and distributed according to the terms of the
 * GNU General Public License version 2 or any later version.
 */

#ifndef HGCLIENT_H_
#define HGCLIENT_H_

#include <sys/types.h>

struct hgclient_tag_;
typedef struct hgclient_tag_ hgclient_t;

hgclient_t *hgc_open(const char *sockname);
void hgc_close(hgclient_t *hgc);

pid_t hgc_peerpgid(const hgclient_t *hgc);
pid_t hgc_peerpid(const hgclient_t *hgc);

const char **hgc_validate(hgclient_t *hgc, const char *const args[],
                          size_t argsize);
int hgc_runcommand(hgclient_t *hgc, const char *const args[], size_t argsize);
void hgc_attachio(hgclient_t *hgc);
void hgc_setenv(hgclient_t *hgc, const char *const envp[]);

#endif /* HGCLIENT_H_ */