Make repo locking an atomic process and added timeout argument

The repo locking function now use a lock directory instead of a lock
file.  This makes the lock checking and creation an atomic process.
The repo_lock function will now try to obtain a lock every $LOCK_DELAY
seconds until it is successful.  An optional third argument can be use
to give a timeout in seconds; this is intended for scripts that runs
unattended.  Repo locking is now used in the ftpdir-cleanup script.
This should fix the problem of the ftpdir-cleanup script removing the
new package instead of the old one (FS#17058).

Signed-off-by: Eric Bélanger <snowmaniscool@gmail.com>

3 files changed, 42 insertions, 19 deletions

diff --git a/config b/config
index 8e582d9..a563f35 100644
--- a/config
+++ b/config
@@ -8,6 +8,9 @@ CLEANUP_DESTDIR="/srv/package-cleanup"
 CLEANUP_DRYRUN=false
 SOURCE_CLEANUP_DESTDIR="/srv/source-cleanup"
 
+LOCK_DELAY=10
+LOCK_TIMEOUT=300
+
 STAGING="$HOME/staging"
 TMPDIR="/srv/tmp"
 ARCHES=(i686 x86_64)
diff --git a/db-functions b/db-functions
index c27366c..df50f22 100644
--- a/db-functions
+++ b/db-functions
@@ -15,27 +15,43 @@ restore_umask () {
 	umask $UMASK
 }
 
-repo_lock () { #repo_lock repo-name arch
-	LOCKFILE="$TMPDIR/.repolock.$1.$2"
-	if [ -f "$LOCKFILE" ]; then
-		owner="$(/usr/bin/stat -c %U $LOCKFILE)"
-		echo "error: db generation is already in progress (started by $owner)" >&2
-		exit 1
-	else
-		/bin/touch "$LOCKFILE"
-		if [ ! -f "$LOCKFILE" ]; then
-			echo "error: could not create repo lock... something went wrong!" >&2
-		fi
-		set_umask
+repo_lock () { #repo_lock <repo-name> <arch> [timeout]
+	LOCKDIR="$TMPDIR/.repolock.$1.$2"
+	local _count
+	local _trial
+	local _timeout
+	local _lockblock
+	local _owner
+
+	if [ $# -eq 2 ]; then
+	    _lockblock=true
+	    _trial=0
+	elif [ $# -eq 3 ]; then
+	    _lockblock=false
+	    _timeout=$3
+	    let _trial=$_timeout/$LOCK_DELAY
 	fi
+
+	_count=0
+	while [ $_count -le $_trial ] || $_lockblock ; do
+	    if ! mkdir "$LOCKDIR" >/dev/null 2>&1 ; then
+		_owner="$(/usr/bin/stat -c %U $LOCKDIR)"
+		echo "error: Repo $1-$2 is already locked by $_owner. Retrying in $LOCK_DELAY seconds..." >&2
+	    else
+		set_umask
+		break
+	    fi
+	    sleep $LOCK_DELAY
+	    let _count=$_count+1
+	done
 }
 
-repo_unlock () { #repo_unlock repo-name arch
-	LOCKFILE="$TMPDIR/.repolock.$1.$2"
-	if [ ! -f "$LOCKFILE" ]; then
+repo_unlock () { #repo_unlock <repo-name> <arch>
+	LOCKDIR="$TMPDIR/.repolock.$1.$2"
+	if [ ! -d "$LOCKDIR" ]; then
 		echo "error: repo lock doesn't exist... something went terribly wrong!" >&2
 	else
-		rm -f "$LOCKFILE"
+		rmdir "$LOCKDIR"
 	fi
 	restore_umask
 }
diff --git a/misc-scripts/ftpdir-cleanup b/misc-scripts/ftpdir-cleanup
index a185090..4c559b9 100755
--- a/misc-scripts/ftpdir-cleanup
+++ b/misc-scripts/ftpdir-cleanup
@@ -10,7 +10,7 @@ dest=$2
 
 ############################################################
 
-. "$(dirname $0)/../db-functions" 
+. "$(dirname $0)/../db-functions"
 . "$(dirname $0)/../config"
 
 ${CLEANUP_DRYRUN} && echo 'dry run mode is active'
@@ -19,6 +19,8 @@ ftppath_base="$FTP_BASE/$reponame/$FTP_OS_SUFFIX"
 
 for arch in ${ARCHES[@]}; do
 
+  repo_lock $reponame $arch $LOCK_TIMEOUT
+
   TMPDIR=$(mktemp -d /tmp/cleanup-XXXXXX) || exit 1
   ftppath="$ftppath_base/$arch"
   MISSINGFILES=""
@@ -80,10 +82,10 @@ for arch in ${ARCHES[@]}; do
           dbpkgname=$(grep -A1 '^%FILENAME%$' "${p}/desc" 2>/dev/null| tail -n1)
           if [ "${dbpkgname}" = "${pkgname}" ]; then
               continue 2
-          fi                                                                                                                                               
+          fi
       done
       EXTRAFILES="$EXTRAFILES $pkg"
-  done 
+  done
 
   rm -rf ${TMPDIR}
 
@@ -100,6 +102,8 @@ for arch in ${ARCHES[@]}; do
       fi
   done
 
+  repo_unlock $reponame $arch
+
   #Make sure we've done *something* before outputting anything
   if [ -z "$DELETEFILES$DELETESYMLINKS$MISSINGFILES$EXTRAFILES" ]; then
       continue