# HG changeset patch
# User Phil Cohen <phil...@fb.com>
# Date 1489995201 25200
# Mon Mar 20 00:33:21 2017 -0700
# Node ID 1ca023fb02cbe4747e2b5b625866cfa538cbebd3
# Parent 2c1d5a02ec533055f182b0cc1280107fbfb76206
lock: add ability to store additional metadata on filesytem
The metadata is written to <lock>.info while the lock is held. It can be
inspected by outside processes to better understand what the lock-holding
process is doing in cases when the PID alone is not enough.
Some examples might include:
- Getting the original command line `hg` is running when the lockholding process
was a originally `chg` process.
- Finding out what command an `hg` process is running without having to parse
its command line yourself.
diff --git a/mercurial/lock.py b/mercurial/lock.py
--- a/mercurial/lock.py
+++ b/mercurial/lock.py
@@ -59,8 +59,10 @@
_host = None
+ # `metadata` is written to a <lockname>.info file while the lock is held
def __init__(self, vfs, file, timeout=-1, releasefn=None, acquirefn=None,
- desc=None, inheritchecker=None, parentlock=None):
+ desc=None, inheritchecker=None, parentlock=None,
+ metadata=None):
self.vfs = vfs
self.f = file
self.held = 0
@@ -70,6 +72,7 @@
self.desc = desc
self._inheritchecker = inheritchecker
self.parentlock = parentlock
+ self.metadata = metadata
self._parentheld = False
self._inherited = False
self.postrelease = []
@@ -128,6 +131,8 @@
try:
self.vfs.makelock(lockname, self.f)
self.held = 1
+ if self.metadata is not None:
+ self.vfs.write(self.f + '.info', self.metadata)
except (OSError, IOError) as why:
if why.errno == errno.EEXIST:
locker = self._readlock()
@@ -248,6 +253,7 @@
if not self._parentheld:
try:
self.vfs.unlink(self.f)
+ self.vfs.unlink(self.f + '.info')
except OSError:
pass
# The postrelease functions typically assume the lock is not held
diff --git a/tests/test-lock-meta.t b/tests/test-lock-meta.t
new file mode 100644
--- /dev/null
+++ b/tests/test-lock-meta.t
@@ -0,0 +1,36 @@
+Make a repo
+
+ $ hg init test
+ $ cd test
+ $ echo file > file
+ $ hg commit -Aqm initial
+
+Make an extension
+
+ $ cat << EOT > lockinfo.py
+ > from contextlib import nested
+ > from mercurial import (cmdutil, extensions, lock)
+ > cmdtable = {}
+ > command = cmdutil.command(cmdtable)
+ > @command('locktest')
+ > def locktest(ui, repo, *args, **opts):
+ > def readf(path):
+ > try:
+ > with open(path, "r") as f:
+ > return f.read()
+ > except IOError as e:
+ > return "<not found>"
+ > def status(str):
+ > print(str, readf(".hg/customlock.info"))
+ > with lock.lock(repo.vfs, "customlock"):
+ > status("No metadata passed; file should not exist")
+ > with lock.lock(repo.vfs, "customlock", metadata="/arbitrary/data"):
+ > status("Should have an info file.")
+ > status("Should be deleted.")
+ > EOT
+
+Test store and write lock
+ $ hg locktest --config extensions.x=lockinfo.py
+ ('No metadata passed; file should not exist', '<not found>')
+ ('Should have an info file.', '/arbitrary/data')
+ ('Should be deleted.', '<not found>')
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