upstream/mercurial-mirror Files · contrib/perf-utils/discovery-helper.sh

posix: always seek to EOF when opening a file in append mode...

posix: always seek to EOF when opening a file in append mode Python 3 already does this, so skip it there. Consider the program: #include <stdio.h> int main() { FILE *f = fopen("narf", "w"); fprintf(f, "narf\n"); fclose(f); f = fopen("narf", "a"); printf("%ld\n", ftell(f)); fprintf(f, "troz\n"); printf("%ld\n", ftell(f)); return 0; } on macOS, FreeBSD, and Linux with glibc, this program prints 5 10 but on musl libc (Alpine Linux and probably others) this prints 0 10 By my reading of https://pubs.opengroup.org/onlinepubs/009695399/functions/fopen.html this is technically correct, specifically: > Opening a file with append mode (a as the first character in the > mode argument) shall cause all subsequent writes to the file to be > forced to the then current end-of-file, regardless of intervening > calls to fseek(). in other words, the file position doesn't really matter in append-mode files, and we can't depend on it being at all meaningful unless we perform a seek() before tell() after open(..., 'a'). Experimentally after a .write() we can do a .tell() and it'll always be reasonable, but I'm unclear from reading the specification if that's a smart thing to rely on. This matches what we do on Windows and what Python 3 does for free, so let's just be consistent. Thanks to Yuya for the idea.

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             discovery-helper.sh
        
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      #!/bin/bash

      #

      # produces two repositories with different common and missing subsets

      #

      #   $ discovery-helper.sh REPO NBHEADS DEPT

      #

      # The Goal is to produce two repositories with some common part and some

      # exclusive part on each side. Provide a source repository REPO, it will

      # produce two repositories REPO-left and REPO-right.

      #

      # Each repository will be missing some revisions exclusive to NBHEADS of the

      # repo topological heads. These heads and revisions exclusive to them (up to

      # DEPTH depth) are stripped.

      #

      # The "left" repository will use the NBHEADS first heads (sorted by

      # description). The "right" use the last NBHEADS one.

      #

      # To find out how many topological heads a repo has, use:

      #

      #   $ hg heads -t -T '{rev}\n' | wc -l

      #

      # Example:

      #

      #  The `pypy-2018-09-01` repository has 192 heads. To produce two repositories

      #  with 92 common heads and ~50 exclusive heads on each side.

      #

      #    $ ./discovery-helper.sh pypy-2018-08-01 50 10

      set -euo pipefail

      printusage () {

           echo "usage: `basename $0` REPO NBHEADS DEPTH [left|right]" >&2

      }

      if [ $# -lt 3 ]; then

          printusage

          exit 64

      fi

      repo="$1"

      shift

      nbheads="$1"

      shift

      depth="$1"

      shift

      doleft=1

      doright=1

      if [ $# -gt 1 ]; then

          printusage

          exit 64

      elif [ $# -eq 1 ]; then

          if [ "$1" == "left" ]; then

              doleft=1

              doright=0

          elif [ "$1" == "right" ]; then

              doleft=0

              doright=1

          else

              printusage

              exit 64

          fi

      fi

      leftrepo="${repo}-${nbheads}h-${depth}d-left"

      rightrepo="${repo}-${nbheads}h-${depth}d-right"

      left="first(sort(heads(all()), 'desc'), $nbheads)"

      right="last(sort(heads(all()), 'desc'), $nbheads)"

      leftsubset="ancestors($left, $depth) and only($left, heads(all() - $left))"

      rightsubset="ancestors($right, $depth) and only($right, heads(all() - $right))"

      echo '### creating left/right repositories with missing changesets:'

      if [ $doleft -eq 1 ]; then

          echo '# left  revset:' '"'${leftsubset}'"'

      fi

      if [ $doright -eq 1 ]; then

          echo '# right revset:' '"'${rightsubset}'"'

      fi

      buildone() {

          side="$1"

          dest="$2"

          revset="$3"

          echo "### building $side repository: $dest"

          if [ -e "$dest" ]; then

              echo "destination repo already exists: $dest" >&2

              exit 1

          fi

          echo '# cloning'

          if ! cp --recursive --reflink=always ${repo} ${dest}; then

              hg clone --noupdate "${repo}" "${dest}"

          fi

          echo '# stripping' '"'${revset}'"'

          hg -R "${dest}" --config extensions.strip= strip --rev "$revset" --no-backup

      }

      if [ $doleft -eq 1 ]; then

          buildone left "$leftrepo" "$leftsubset"

      fi

      if [ $doright -eq 1 ]; then

          buildone right "$rightrepo" "$rightsubset"

      fi

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				#!/bin/bash
				#
				# produces two repositories with different common and missing subsets
				#
				# $ discovery-helper.sh REPO NBHEADS DEPT
				#
				# The Goal is to produce two repositories with some common part and some
				# exclusive part on each side. Provide a source repository REPO, it will
				# produce two repositories REPO-left and REPO-right.
				#
				# Each repository will be missing some revisions exclusive to NBHEADS of the
				# repo topological heads. These heads and revisions exclusive to them (up to
				# DEPTH depth) are stripped.
				#
				# The "left" repository will use the NBHEADS first heads (sorted by
				# description). The "right" use the last NBHEADS one.
				#
				# To find out how many topological heads a repo has, use:
				#
				# $ hg heads -t -T '{rev}\n' \| wc -l
				#
				# Example:
				#
				# The `pypy-2018-09-01` repository has 192 heads. To produce two repositories
				# with 92 common heads and ~50 exclusive heads on each side.
				#
				# $ ./discovery-helper.sh pypy-2018-08-01 50 10

				set -euo pipefail

				printusage () {
				echo "usage: `basename $0` REPO NBHEADS DEPTH [left\|right]" >&2
				}

				if [ $# -lt 3 ]; then
				printusage
				exit 64
				fi

				repo="$1"
				shift

				nbheads="$1"
				shift

				depth="$1"
				shift

				doleft=1
				doright=1
				if [ $# -gt 1 ]; then
				printusage
				exit 64
				elif [ $# -eq 1 ]; then
				if [ "$1" == "left" ]; then
				doleft=1
				doright=0
				elif [ "$1" == "right" ]; then
				doleft=0
				doright=1
				else
				printusage
				exit 64
				fi
				fi

				leftrepo="${repo}-${nbheads}h-${depth}d-left"
				rightrepo="${repo}-${nbheads}h-${depth}d-right"

				left="first(sort(heads(all()), 'desc'), $nbheads)"
				right="last(sort(heads(all()), 'desc'), $nbheads)"

				leftsubset="ancestors($left, $depth) and only($left, heads(all() - $left))"
				rightsubset="ancestors($right, $depth) and only($right, heads(all() - $right))"

				echo '### creating left/right repositories with missing changesets:'
				if [ $doleft -eq 1 ]; then
				echo '# left revset:' '"'${leftsubset}'"'
				fi
				if [ $doright -eq 1 ]; then
				echo '# right revset:' '"'${rightsubset}'"'
				fi

				buildone() {
				side="$1"
				dest="$2"
				revset="$3"
				echo "### building $side repository: $dest"
				if [ -e "$dest" ]; then
				echo "destination repo already exists: $dest" >&2
				exit 1
				fi
				echo '# cloning'
				if ! cp --recursive --reflink=always ${repo} ${dest}; then
				hg clone --noupdate "${repo}" "${dest}"
				fi
				echo '# stripping' '"'${revset}'"'
				hg -R "${dest}" --config extensions.strip= strip --rev "$revset" --no-backup
				}

				if [ $doleft -eq 1 ]; then
				buildone left "$leftrepo" "$leftsubset"
				fi

				if [ $doright -eq 1 ]; then
				buildone right "$rightrepo" "$rightsubset"
				fi