lib.fileset: Refactor inotify testing to be reusable
This commit is contained in:
Silvan Mosberger
parent
5bbe67bf67
commit
692b75257e
@ -147,16 +147,83 @@ expectTrace() {
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fi
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}
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# We conditionally use inotifywait in checkFileset.
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# We conditionally use inotifywait in withFileMonitor.
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# Check early whether it's available
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# TODO: Darwin support, though not crucial since we have Linux CI
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if type inotifywait 2>/dev/null >/dev/null; then
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canMonitorFiles=1
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canMonitor=1
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else
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echo "Warning: Not checking that excluded files don't get accessed since inotifywait is not available" >&2
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canMonitorFiles=
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echo "Warning: Cannot check for paths not getting read since the inotifywait command (from the inotify-tools package) is not available" >&2
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canMonitor=
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fi
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# Run a function while monitoring that it doesn't read certain paths
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# Usage: withFileMonitor FUNNAME PATH...
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# - FUNNAME should be a bash function that:
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# - Performs some operation that should not read some paths
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# - Delete the paths it shouldn't read without triggering any open events
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# - PATH... are the paths that should not get read
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#
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# This function outputs the same as FUNNAME
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withFileMonitor() {
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local funName=$1
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shift
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# If we can't monitor files or have none to monitor, just run the function directly
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if [[ -z "$canMonitor" ]] || (( "$#" == 0 )); then
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"$funName"
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else
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# Use a subshell to start the coprocess in and use a trap to kill it when exiting the subshell
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(
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# Assigned by coproc, makes shellcheck happy
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local watcher watcher_PID
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# Start inotifywait in the background to monitor all excluded paths
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coproc watcher {
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# inotifywait outputs a string on stderr when ready
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# Redirect it to stdout so we can access it from the coproc's stdout fd
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# exec so that the coprocess is inotify itself, making the kill below work correctly
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# See below why we listen to both open and delete_self events
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exec inotifywait --format='%e %w' --event open,delete_self --monitor "$@" 2>&1
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}
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# This will trigger when this subshell exits, no matter if successful or not
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# After exiting the subshell, the parent shell will continue executing
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trap 'kill "${watcher_PID}"' exit
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# Synchronously wait until inotifywait is ready
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while read -r -u "${watcher[0]}" line && [[ "$line" != "Watches established." ]]; do
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:
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done
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# Call the function that should not read the given paths and delete them afterwards
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"$funName"
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# Get the first event
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read -r -u "${watcher[0]}" event file
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# With funName potentially reading files first before deleting them,
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# there's only these two possible event timelines:
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# - open*, ..., open*, delete_self, ..., delete_self: If some excluded paths were read
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# - delete_self, ..., delete_self: If no excluded paths were read
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# So by looking at the first event we can figure out which one it is!
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# This also means we don't have to wait to collect all events.
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case "$event" in
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OPEN*)
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die "$funName opened excluded file $file when it shouldn't have"
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;;
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DELETE_SELF)
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# Expected events
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;;
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*)
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die "During $funName, Unexpected event type '$event' on file $file that should be excluded"
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;;
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esac
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)
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fi
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}
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# Check whether a file set includes/excludes declared paths as expected, usage:
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#
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# tree=(
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@ -166,7 +233,7 @@ fi
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# )
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# checkFileset './a' # Pass the fileset as the argument
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declare -A tree
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checkFileset() (
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checkFileset() {
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# New subshell so that we can have a separate trap handler, see `trap` below
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local fileset=$1
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@ -214,54 +281,21 @@ checkFileset() (
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touch "${filesToCreate[@]}"
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fi
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# Start inotifywait in the background to monitor all excluded files (if any)
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if [[ -n "$canMonitorFiles" ]] && (( "${#excludedFiles[@]}" != 0 )); then
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coproc watcher {
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# inotifywait outputs a string on stderr when ready
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# Redirect it to stdout so we can access it from the coproc's stdout fd
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# exec so that the coprocess is inotify itself, making the kill below work correctly
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# See below why we listen to both open and delete_self events
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exec inotifywait --format='%e %w' --event open,delete_self --monitor "${excludedFiles[@]}" 2>&1
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}
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# This will trigger when this subshell exits, no matter if successful or not
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# After exiting the subshell, the parent shell will continue executing
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# shellcheck disable=SC2154
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trap 'kill "${watcher_PID}"' exit
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# Synchronously wait until inotifywait is ready
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while read -r -u "${watcher[0]}" line && [[ "$line" != "Watches established." ]]; do
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:
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done
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fi
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# Call toSource with the fileset, triggering open events for all files that are added to the store
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expression="toSource { root = ./.; fileset = $fileset; }"
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storePath=$(expectStorePath "$expression")
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# Remove all files immediately after, triggering delete_self events for all of them
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rm -rf -- *
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# We don't have lambda's in bash unfortunately,
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# so we just define a function instead and then pass its name
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# shellcheck disable=SC2317
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run() {
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# Call toSource with the fileset, triggering open events for all files that are added to the store
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expectStorePath "$expression"
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if (( ${#excludedFiles[@]} != 0 )); then
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rm "${excludedFiles[@]}"
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fi
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}
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# Only check for the inotify events if we actually started inotify earlier
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if [[ -v watcher ]]; then
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# Get the first event
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read -r -u "${watcher[0]}" event file
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# There's only these two possible event timelines:
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# - open, ..., open, delete_self, ..., delete_self: If some excluded files were read
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# - delete_self, ..., delete_self: If no excluded files were read
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# So by looking at the first event we can figure out which one it is!
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case "$event" in
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OPEN)
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die "$expression opened excluded file $file when it shouldn't have"
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;;
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DELETE_SELF)
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# Expected events
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;;
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*)
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die "Unexpected event type '$event' on file $file that should be excluded"
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;;
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esac
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fi
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# Runs the function while checking that the given excluded files aren't read
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storePath=$(withFileMonitor run "${excludedFiles[@]}")
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# For each path that should be included, make sure it does occur in the resulting store path
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for p in "${included[@]}"; do
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@ -276,7 +310,9 @@ checkFileset() (
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die "$expression included path $p when it shouldn't have"
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fi
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done
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)
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rm -rf -- *
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}
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#### Error messages #####
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