dirstate-tree: Make `DirstateMap` borrow from a bytes buffer
… that has the contents of the `.hg/dirstate` file.
This only applies to the tree-based flavor of `DirstateMap`.
For now only the entire `&[u8]` slice is stored, so this is not useful yet.
Adding a lifetime parameter to the `DirstateMap` struct (in hg-core) makes
Python bindings non-trivial because we keep that struct in a Python object
that has a dynamic lifetime tied to Python’s reference-counting and GC.
As long as we keep the `PyBytes` that owns the borrowed bytes buffer next to
the borrowing struct, the buffer will live long enough for the borrows to stay
valid. However this relationship cannot be expressed in safe Rust code in a
way that would statisfy they borrow-checker. We use `unsafe` code to erase
that lifetime parameter, and encapsulate it in a safe abstraction similar to
the owning-ref crate: https://docs.rs/owning_ref/
Differential Revision: https://phab.mercurial-scm.org/D10557
#!/usr/bin/env python3
#
# Dumps output generated by Mercurial's command server in a formatted style to a
# given file or stderr if '-' is specified. Output is also written in its raw
# format to stdout.
#
# $ ./hg serve --cmds pipe | ./contrib/debugcmdserver.py -
# o, 52 -> 'capabilities: getencoding runcommand\nencoding: UTF-8'
from __future__ import absolute_import, print_function
import struct
import sys
if len(sys.argv) != 2:
print('usage: debugcmdserver.py FILE')
sys.exit(1)
outputfmt = '>cI'
outputfmtsize = struct.calcsize(outputfmt)
if sys.argv[1] == '-':
log = sys.stderr
else:
log = open(sys.argv[1], 'a')
def read(size):
data = sys.stdin.read(size)
if not data:
raise EOFError
sys.stdout.write(data)
sys.stdout.flush()
return data
try:
while True:
header = read(outputfmtsize)
channel, length = struct.unpack(outputfmt, header)
log.write('%s, %-4d' % (channel, length))
if channel in 'IL':
log.write(' -> waiting for input\n')
else:
data = read(length)
log.write(' -> %r\n' % data)
log.flush()
except EOFError:
pass
finally:
if log != sys.stderr:
log.close()