[PATCH] Use the Xapian::DB_RETRY_LOCK flag when available

[Istvan Marko <notmuch@kismala.com>]

Xapian 1.3 has introduced the DB_RETRY_LOCK flag (Xapian bug
275). Detect it in configure and use it if available. With this flag
commands that need the write lock will wait for their turn instead of
aborting when it's not immediately available.
---
 configure       | 25 ++++++++++++++++++++++++-
 lib/database.cc |  5 +++++
 2 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/configure b/configure
index 6231d2b..0c1d5bc 100755
--- a/configure
+++ b/configure
@@ -371,6 +371,21 @@ if [ ${have_xapian} = "1" ]; then
     esac
 fi
 
+# DB_RETRY_LOCK is only supported on Xapian > 1.3.2
+have_xapian_db_retry_lock=0
+if [ ${have_xapian} = "1" ]; then
+    printf "Checking for Xapian lock retry support... "
+    case "${xapian_version}" in
+	0.*|1.[012].*|1.3.[0-2])
+	    printf "No (only available with Xapian > 1.3.2).\n" ;;
+	[1-9]*.[0-9]*.[0-9]*)
+	    have_xapian_db_retry_lock=1
+	    printf "Yes.\n" ;;
+	*)
+	    printf "Unknown version.\n" ;;
+    esac
+fi
+
 default_xapian_backend=""
 if [ ${have_xapian} = "1" ]; then
     printf "Testing default Xapian backend... "
@@ -998,6 +1013,9 @@ HAVE_D_TYPE = ${have_d_type}
 # Whether the Xapian version in use supports compaction
 HAVE_XAPIAN_COMPACT = ${have_xapian_compact}
 
+# Whether the Xapian version in use supports DB_RETRY_LOCK
+HAVE_XAPIAN_DB_RETRY_LOCK = ${have_xapian_db_retry_lock}
+
 # Whether the getpwuid_r function is standards-compliant
 # (if not, then notmuch will #define _POSIX_PTHREAD_SEMANTICS
 # to enable the standards-compliant version -- needed for Solaris)
@@ -1072,6 +1090,7 @@ CONFIGURE_CFLAGS = -DHAVE_GETLINE=\$(HAVE_GETLINE) \$(GMIME_CFLAGS)      \\
 		   -DSTD_GETPWUID=\$(STD_GETPWUID)                       \\
 		   -DSTD_ASCTIME=\$(STD_ASCTIME)                         \\
 		   -DHAVE_XAPIAN_COMPACT=\$(HAVE_XAPIAN_COMPACT)	 \\
+		   -DHAVE_XAPIAN_DB_RETRY_LOCK=\$(HAVE_XAPIAN_DB_RETRY_LOCK) \\
 		   -DUTIL_BYTE_ORDER=\$(UTIL_BYTE_ORDER)
 
 CONFIGURE_CXXFLAGS = -DHAVE_GETLINE=\$(HAVE_GETLINE) \$(GMIME_CFLAGS)    \\
@@ -1086,6 +1105,7 @@ CONFIGURE_CXXFLAGS = -DHAVE_GETLINE=\$(HAVE_GETLINE) \$(GMIME_CFLAGS)    \\
 		     -DSTD_GETPWUID=\$(STD_GETPWUID)                     \\
 		     -DSTD_ASCTIME=\$(STD_ASCTIME)                       \\
 		     -DHAVE_XAPIAN_COMPACT=\$(HAVE_XAPIAN_COMPACT)       \\
+                     -DHAVE_XAPIAN_DB_RETRY_LOCK=\$(HAVE_XAPIAN_DB_RETRY_LOCK) \\
 		     -DUTIL_BYTE_ORDER=\$(UTIL_BYTE_ORDER)
 
 CONFIGURE_LDFLAGS =  \$(GMIME_LDFLAGS) \$(TALLOC_LDFLAGS) \$(ZLIB_LDFLAGS) \$(XAPIAN_LDFLAGS)
@@ -1097,7 +1117,10 @@ cat > sh.config <<EOF
 # script of notmuch.
 
 # Whether the Xapian version in use supports compaction
-NOTMUCH_HAVE_XAPIAN_COMPACT=${have_xapian_compact}
+NOTMUCH_HAVE_XAPIAN_  =${have_xapian_compact}
+
+# Whether the Xapian version in use supports DB_RETRY_LOCK
+NOTMUCH_HAVE_XAPIAN_DB_RETRY_LOCK=${have_xapian_db_retry_lock}
 
 # Which backend will Xapian use by default?
 NOTMUCH_DEFAULT_XAPIAN_BACKEND=${default_xapian_backend}
diff --git a/lib/database.cc b/lib/database.cc
index c8c5e26..4b503a2 100644
--- a/lib/database.cc
+++ b/lib/database.cc
@@ -929,8 +929,13 @@ notmuch_database_open_verbose (const char *path,
 	string last_mod;
 
 	if (mode == NOTMUCH_DATABASE_MODE_READ_WRITE) {
+	    #if HAVE_XAPIAN_DB_RETRY_LOCK
+	    notmuch->xapian_db = new Xapian::WritableDatabase (xapian_path,
+							       Xapian::DB_CREATE_OR_OPEN|Xapian::DB_RETRY_LOCK);
+	    #else
 	    notmuch->xapian_db = new Xapian::WritableDatabase (xapian_path,
 							       Xapian::DB_CREATE_OR_OPEN);
+	    #endif
 	} else {
 	    notmuch->xapian_db = new Xapian::Database (xapian_path);
 	}
-- 
2.4.10


-- 
	Istvan