upstream/mercurial-mirror Files · contrib/memory.py

cmdutil: add class to restore dirstate during unexpected failure...

cmdutil: add class to restore dirstate during unexpected failure Before this patch, after "dirstate.write()" execution, there was no way to restore dirstate to the original status before "dirstate.write()". In some code paths, "dirstate.invalidate()" is used as a kind of "restore .hg/dirstate to the original status", but it just avoids writing changes in memory out, and doesn't actually restore the ".hg/dirstate" file. To fix the issue that the recent (in memory) dirstate isn't visible to external processes (e.g. "precommit" hooks), "dirstate.write()" should be invoked before invocation of external processes. But at the same time, ".hg/dirstate" should be restored to its content before "dirstate.write()" during an unexpected failure in some cases. This patch adds the class "dirstateguard" to easily restore ".hg/dirstate" during unexpected failures. Typical usecase of it is: # (1) build dirstate up .... # (2) write dirstate out, and backup ".hg/dirstate" dsguard = dirstateguard(repo, 'scopename') try: # (3) execute somethig to do: # this may imply making some additional changes on dirstate .... # (4) unlink backed-up dirstate file at the end of dsguard scope dsguard.close() finally: # (5) if execution is aborted before "dsguard.close()", # ".hg/dirstate" is restored from the backup dsguard.release() For this kind of issue, an "extending transaction" approach (in https://titanpad.com/mercurial32-sprint) seems to not be suitable, because: - transaction nesting occurs in some cases (e.g. "shelve => rebase"), and - "dirstate" may be already modified since the beginning of OUTER transaction scope, then - dirstate should be backed up into the file other than "dirstate.journal" at the beginning of INNER transaction scope, but - such alternative backup files are useless for transaction itself, and increases complication of its implementation "transaction" and "dirstateguard" differ from each other also in "what it should do for .hg/dirstate" in cases other than success. ============== ======= ======== ============= type success fail "hg rollback" ============== ======= ======== ============= transaction keep keep restore dirstateguard keep restore (not implied) ============== ======= ======== ============= Some collaboration between transaction and dirstate will probably be introduced in the future. But this layer is needed in all cases.

Matt Mackall - - Load All Authors

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      # memory.py - track memory usage

      #

      # Copyright 2009 Matt Mackall <mpm@selenic.com> and others

      #

      # This software may be used and distributed according to the terms of the

      # GNU General Public License version 2 or any later version.

      '''helper extension to measure memory usage

      Reads current and peak memory usage from ``/proc/self/status`` and

      prints it to ``stderr`` on exit.

      '''

      import atexit

      def memusage(ui):

          """Report memory usage of the current process."""

          status = None

          result = {'peak': 0, 'rss': 0}

          try:

              # This will only work on systems with a /proc file system

              # (like Linux).

              status = open('/proc/self/status', 'r')

              for line in status:

                  parts = line.split()

                  key = parts[0][2:-1].lower()

                  if key in result:

                      result[key] = int(parts[1])

          finally:

              if status is not None:

                  status.close()

          ui.write_err(", ".join(["%s: %.1f MiB" % (key, value / 1024.0)

                                  for key, value in result.iteritems()]) + "\n")

      def extsetup(ui):

          atexit.register(memusage, ui)

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				# memory.py - track memory usage
				#
				# Copyright 2009 Matt Mackall <mpm@selenic.com> and others
				#
				# This software may be used and distributed according to the terms of the
				# GNU General Public License version 2 or any later version.

				'''helper extension to measure memory usage

				Reads current and peak memory usage from ``/proc/self/status`` and
				prints it to ``stderr`` on exit.
				'''

				import atexit

				def memusage(ui):
				"""Report memory usage of the current process."""
				status = None
				result = {'peak': 0, 'rss': 0}
				try:
				# This will only work on systems with a /proc file system
				# (like Linux).
				status = open('/proc/self/status', 'r')
				for line in status:
				parts = line.split()
				key = parts[0][2:-1].lower()
				if key in result:
				result[key] = int(parts[1])
				finally:
				if status is not None:
				status.close()
				ui.write_err(", ".join(["%s: %.1f MiB" % (key, value / 1024.0)
				for key, value in result.iteritems()]) + "\n")

				def extsetup(ui):
				atexit.register(memusage, ui)