view contrib/chg/util.c @ 48178:f12a19d03d2c

fix: reduce number of tool executions

By grouping together (path, ctx) pairs according to the inputs they would
provide to fixer tools, we can deduplicate executions of fixer tools to
significantly reduce the amount of time spent running slow tools.

This change does not handle clean files in the working copy, which could still
be deduplicated against the files in the checked out commit. It's a little
harder to do that because the filerev is not available in the workingfilectx
(and it doesn't exist for added files).

Anecdotally, this change makes some real uses cases at Google 10x faster. I
think we were originally hesitant to do this because the benefits weren't
obvious, and implementing it efficiently is kind of tricky. If we simply
memoized the formatter execution function, we would be keeping tons of file
content in memory.

Also included is a regression test for a corner case that I broke with my first
attempt at optimizing this code.

Differential Revision: https://phab.mercurial-scm.org/D11280

/*
 * Utility functions
 *
 * 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.
 */

#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>

#include "util.h"

static int colorenabled = 0;

static inline void fsetcolor(FILE *fp, const char *code)
{
	if (!colorenabled) {
		return;
	}
	fprintf(fp, "\033[%sm", code);
}

static void vabortmsgerrno(int no, const char *fmt, va_list args)
{
	fsetcolor(stderr, "1;31");
	fputs("chg: abort: ", stderr);
	vfprintf(stderr, fmt, args);
	if (no != 0) {
		fprintf(stderr, " (errno = %d, %s)", no, strerror(no));
	}
	fsetcolor(stderr, "");
	fputc('\n', stderr);
	exit(255);
}

void abortmsg(const char *fmt, ...)
{
	va_list args;
	va_start(args, fmt);
	vabortmsgerrno(0, fmt, args);
	va_end(args);
}

void abortmsgerrno(const char *fmt, ...)
{
	int no = errno;
	va_list args;
	va_start(args, fmt);
	vabortmsgerrno(no, fmt, args);
	va_end(args);
}

static int debugmsgenabled = 0;
static double debugstart = 0;

static double now()
{
	struct timeval t;
	gettimeofday(&t, NULL);
	return t.tv_usec / 1e6 + t.tv_sec;
}

void enablecolor(void)
{
	colorenabled = 1;
}

void enabledebugmsg(void)
{
	debugmsgenabled = 1;
	debugstart = now();
}

void debugmsg(const char *fmt, ...)
{
	if (!debugmsgenabled) {
		return;
	}

	va_list args;
	va_start(args, fmt);
	fsetcolor(stderr, "1;30");
	fprintf(stderr, "chg: debug: %4.6f ", now() - debugstart);
	vfprintf(stderr, fmt, args);
	fsetcolor(stderr, "");
	fputc('\n', stderr);
	va_end(args);
}

void fchdirx(int dirfd)
{
	int r = fchdir(dirfd);
	if (r == -1) {
		abortmsgerrno("failed to fchdir");
	}
}

void fsetcloexec(int fd)
{
	int flags = fcntl(fd, F_GETFD);
	if (flags < 0) {
		abortmsgerrno("cannot get flags of fd %d", fd);
	}
	if (fcntl(fd, F_SETFD, flags | FD_CLOEXEC) < 0) {
		abortmsgerrno("cannot set flags of fd %d", fd);
	}
}

void *mallocx(size_t size)
{
	void *result = malloc(size);
	if (!result) {
		abortmsg("failed to malloc");
	}
	return result;
}

void *reallocx(void *ptr, size_t size)
{
	void *result = realloc(ptr, size);
	if (!result) {
		abortmsg("failed to realloc");
	}
	return result;
}

/*
 * Execute a shell command in mostly the same manner as system(), with the
 * give environment variables, after chdir to the given cwd. Returns a status
 * code compatible with the Python subprocess module.
 */
int runshellcmd(const char *cmd, const char *envp[], const char *cwd)
{
	enum { F_SIGINT = 1, F_SIGQUIT = 2, F_SIGMASK = 4, F_WAITPID = 8 };
	unsigned int doneflags = 0;
	int status = 0;
	struct sigaction newsa, oldsaint, oldsaquit;
	sigset_t oldmask;

	/* block or mask signals just as system() does */
	memset(&newsa, 0, sizeof(newsa));
	newsa.sa_handler = SIG_IGN;
	newsa.sa_flags = 0;
	if (sigemptyset(&newsa.sa_mask) < 0) {
		goto done;
	}
	if (sigaction(SIGINT, &newsa, &oldsaint) < 0) {
		goto done;
	}
	doneflags |= F_SIGINT;
	if (sigaction(SIGQUIT, &newsa, &oldsaquit) < 0) {
		goto done;
	}
	doneflags |= F_SIGQUIT;

	if (sigaddset(&newsa.sa_mask, SIGCHLD) < 0) {
		goto done;
	}
	if (sigprocmask(SIG_BLOCK, &newsa.sa_mask, &oldmask) < 0) {
		goto done;
	}
	doneflags |= F_SIGMASK;

	pid_t pid = fork();
	if (pid < 0) {
		goto done;
	}
	if (pid == 0) {
		sigaction(SIGINT, &oldsaint, NULL);
		sigaction(SIGQUIT, &oldsaquit, NULL);
		sigprocmask(SIG_SETMASK, &oldmask, NULL);
		if (cwd && chdir(cwd) < 0) {
			_exit(127);
		}
		const char *argv[] = {"sh", "-c", cmd, NULL};
		if (envp) {
			execve("/bin/sh", (char **)argv, (char **)envp);
		} else {
			execv("/bin/sh", (char **)argv);
		}
		_exit(127);
	} else {
		if (waitpid(pid, &status, 0) < 0) {
			goto done;
		}
		doneflags |= F_WAITPID;
	}

done:
	if (doneflags & F_SIGINT) {
		sigaction(SIGINT, &oldsaint, NULL);
	}
	if (doneflags & F_SIGQUIT) {
		sigaction(SIGQUIT, &oldsaquit, NULL);
	}
	if (doneflags & F_SIGMASK) {
		sigprocmask(SIG_SETMASK, &oldmask, NULL);
	}

	/* no way to report other errors, use 127 (= shell termination) */
	if (!(doneflags & F_WAITPID)) {
		return 127;
	}
	if (WIFEXITED(status)) {
		return WEXITSTATUS(status);
	}
	if (WIFSIGNALED(status)) {
		return -WTERMSIG(status);
	}
	return 127;
}