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Add upgrade locking for macs (#15038)

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jcollins-g 2018-03-02 09:52:14 -08:00 committed by GitHub
parent 1a7eeb34da
commit bcdbed9628
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1 changed files with 25 additions and 10 deletions
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@ -33,7 +33,13 @@ function path_uri() {
echo "$1" | sed -E -e "s,^/+,/,"
}
function _rmlock () {
[ -n "$FLUTTER_UPGRADE_LOCK" ] && rm -f "$FLUTTER_UPGRADE_LOCK"
}
function upgrade_flutter () {
mkdir -p "$FLUTTER_ROOT/bin/cache"
# This function is executed with a redirect that pipes the source of
# this script into file descriptor 3.
#
@ -47,14 +53,14 @@ function upgrade_flutter () {
# file, having inherited the file descriptor from the shell.
#
# Complicating matters, there are two major scenarios where this
# will not work. The first is if the platform doesn't have "flock",
# for example on Mac. There does not appear to be any sort of other
# equivalent, so on platforms that don't have flock, we just don't
# do anything.
# will not work.
#
# To determine if we have "flock" available, we abuse the "hash"
# shell built-in to determine if "flock" resolves to anything. If it
# does, we call it, otherwise we forget the whole thing.
# The first is if the platform doesn't have "flock", for example on Mac.
# There is not a direct equivalent, so on platforms that don't have flock,
# we fall back to using a lockfile and spinlock with "shlock". This
# doesn't work as well over NFS as it relies on PIDs. Any platform
# without either of these tools has no locking at all. To determine if we
# have "flock" or "shlock" available, we abuse the "hash" shell built-in.
#
# The second complication is NFS. On NFS, to obtain an exclusive
# lock you need a file descriptor that is open for writing, because
@ -65,16 +71,20 @@ function upgrade_flutter () {
# users will typically not care about errors from flock and are
# more likely to be confused by them than helped.
#
# The lock is released when the file descriptor goes out of scope,
# i.e. when this function returns.
# For "flock", the lock is released when the file descriptor goes out of
# scope, i.e. when this function returns. The lock is released via
# a trap when using "shlock".
if hash flock 2>/dev/null; then
flock 3 2>/dev/null || true
elif hash shlock 2>/dev/null; then
FLUTTER_UPGRADE_LOCK="$FLUTTER_ROOT/bin/cache/.upgrade_lock"
while ! shlock -f "$FLUTTER_UPGRADE_LOCK" -p $$ ; do sleep .1 ; done
trap _rmlock EXIT
fi
local revision=`(cd "$FLUTTER_ROOT"; git rev-parse HEAD)`
if [ ! -f "$SNAPSHOT_PATH" ] || [ ! -s "$STAMP_PATH" ] || [ `cat "$STAMP_PATH"` != "$revision" ] || [ "$FLUTTER_TOOLS_DIR/pubspec.yaml" -nt "$FLUTTER_TOOLS_DIR/pubspec.lock" ]; then
rm -f "$FLUTTER_ROOT/version"
mkdir -p "$FLUTTER_ROOT/bin/cache"
touch "$FLUTTER_ROOT/bin/cache/.dartignore"
"$FLUTTER_ROOT/bin/internal/update_dart_sdk.sh"
@ -97,6 +107,11 @@ function upgrade_flutter () {
"$DART" --snapshot="$SNAPSHOT_PATH" --packages="$FLUTTER_TOOLS_DIR/.packages" "$SCRIPT_PATH"
echo "$revision" > "$STAMP_PATH"
fi
# The exit here is duplicitous since the function is run in a subshell,
# but this serves as documentation that running the function in a
# subshell is required to make sure any lockfile created by shlock
# is cleaned up.
exit $?
}
PROG_NAME="$(path_uri "$(follow_links "$BASH_SOURCE")")"