branchcache: skip entries that are topological heads in the on disk file
In the majority of cases, topological heads are also branch heads. We have
efficient way to get the topological heads and efficient way to retrieve
their branch information. So there is little value in putting them in the branch
cache file explicitly. On the contrary, writing them explicitly tend to create
very large cache file that are inefficient to read and update.
So the branch cache v3 format is no longer including them. This changeset focus
on the format aspect and have no focus on the performance aspect. We will cover
that later.
# A minimal client for Mercurial's command server
import io
import os
import re
import signal
import socket
import struct
import subprocess
import sys
import time
if sys.version_info[0] >= 3:
stdout = sys.stdout.buffer
stderr = sys.stderr.buffer
stringio = io.BytesIO
def bprint(*args):
# remove b'' as well for ease of test migration
pargs = [re.sub(br'''\bb(['"])''', br'\1', b'%s' % a) for a in args]
stdout.write(b' '.join(pargs) + b'\n')
else:
import cStringIO
stdout = sys.stdout
stderr = sys.stderr
stringio = cStringIO.StringIO
bprint = print
def connectpipe(path=None, extraargs=()):
cmdline = [b'hg', b'serve', b'--cmdserver', b'pipe']
if path:
cmdline += [b'-R', path]
cmdline.extend(extraargs)
def tonative(cmdline):
if os.name != 'nt':
return cmdline
return [arg.decode("utf-8") for arg in cmdline]
server = subprocess.Popen(
tonative(cmdline), stdin=subprocess.PIPE, stdout=subprocess.PIPE
)
return server
class unixconnection:
def __init__(self, sockpath):
self.sock = sock = socket.socket(socket.AF_UNIX)
sock.connect(sockpath)
self.stdin = sock.makefile('wb')
self.stdout = sock.makefile('rb')
def wait(self):
self.stdin.close()
self.stdout.close()
self.sock.close()
class unixserver:
def __init__(self, sockpath, logpath=None, repopath=None):
self.sockpath = sockpath
cmdline = [b'hg', b'serve', b'--cmdserver', b'unix', b'-a', sockpath]
if repopath:
cmdline += [b'-R', repopath]
if logpath:
stdout = open(logpath, 'a')
stderr = subprocess.STDOUT
else:
stdout = stderr = None
self.server = subprocess.Popen(cmdline, stdout=stdout, stderr=stderr)
# wait for listen()
while self.server.poll() is None:
if os.path.exists(sockpath):
break
time.sleep(0.1)
def connect(self):
return unixconnection(self.sockpath)
def shutdown(self):
os.kill(self.server.pid, signal.SIGTERM)
self.server.wait()
def writeblock(server, data):
server.stdin.write(struct.pack(b'>I', len(data)))
server.stdin.write(data)
server.stdin.flush()
def readchannel(server):
data = server.stdout.read(5)
if not data:
raise EOFError
channel, length = struct.unpack('>cI', data)
if channel in b'IL':
return channel, length
else:
return channel, server.stdout.read(length)
def sep(text):
return text.replace(b'\\', b'/')
def runcommand(
server, args, output=stdout, error=stderr, input=None, outfilter=lambda x: x
):
bprint(b'*** runcommand', b' '.join(args))
stdout.flush()
server.stdin.write(b'runcommand\n')
writeblock(server, b'\0'.join(args))
if not input:
input = stringio()
while True:
ch, data = readchannel(server)
if ch == b'o':
output.write(outfilter(data))
output.flush()
elif ch == b'e':
error.write(data)
error.flush()
elif ch == b'I':
writeblock(server, input.read(data))
elif ch == b'L':
writeblock(server, input.readline(data))
elif ch == b'm':
bprint(b"message: %r" % data)
elif ch == b'r':
(ret,) = struct.unpack('>i', data)
if ret != 0:
bprint(b' [%d]' % ret)
return ret
else:
bprint(b"unexpected channel %c: %r" % (ch, data))
if ch.isupper():
return
def check(func, connect=connectpipe):
stdout.flush()
server = connect()
try:
return func(server)
finally:
server.stdin.close()
server.wait()
def checkwith(connect=connectpipe, **kwargs):
def wrap(func):
return check(func, lambda: connect(**kwargs))
return wrap