[bitbake-devel] [PATCH] prserv: don't wait until exit to sync

[Ben Shelton]

In the commit 'prserv: Ensure data is committed', the PR server moved to
only committing transactions to the database when the PR server is
stopped.  This improves performance, but it means that if the machine
running the PR server loses power unexpectedly or if the PR server
process gets SIGKILL, the uncommitted package revision data is lost.

To fix this issue, sync the database periodically, once per 30 seconds
by default, if it has been marked as dirty.  To be safe, continue to
sync the database at exit regardless of its status.

Signed-off-by: Ben Shelton <ben.shelton at ni.com>
---
 lib/prserv/db.py   | 14 ++++++++++++++
 lib/prserv/serv.py |  7 +++++++
 2 files changed, 21 insertions(+)

diff --git a/lib/prserv/db.py b/lib/prserv/db.py
index 49f36da..3bdc046 100644
--- a/lib/prserv/db.py
+++ b/lib/prserv/db.py
@@ -19,6 +19,7 @@ class PRTable(object):
     def __init__(self, conn, table, nohist):
         self.conn = conn
         self.nohist = nohist
+        self.dirty = False
         if nohist:
             self.table = "%s_nohist" % table 
         else:
@@ -47,6 +48,11 @@ class PRTable(object):
         self.conn.commit()
         self._execute("BEGIN EXCLUSIVE TRANSACTION")
 
+    def sync_if_dirty(self):
+        if self.dirty:
+            self.sync()
+            self.dirty = False
+
     def _getValueHist(self, version, pkgarch, checksum):
         data=self._execute("SELECT value FROM %s WHERE version=? AND pkgarch=? AND checksum=?;" % self.table,
                            (version, pkgarch, checksum))
@@ -62,6 +68,8 @@ class PRTable(object):
             except sqlite3.IntegrityError as exc:
                 logger.error(str(exc))
 
+            self.dirty = True
+
             data=self._execute("SELECT value FROM %s WHERE version=? AND pkgarch=? AND checksum=?;" % self.table,
                                (version, pkgarch, checksum))
             row=data.fetchone()
@@ -89,6 +97,8 @@ class PRTable(object):
                 logger.error(str(exc))
                 self.conn.rollback()
 
+            self.dirty = True
+
             data=self._execute("SELECT value FROM %s WHERE version=? AND pkgarch=? AND checksum=?;" % self.table,
                                (version, pkgarch, checksum))
             row=data.fetchone()
@@ -118,6 +128,8 @@ class PRTable(object):
             except sqlite3.IntegrityError as exc:
                 logger.error(str(exc))
 
+            self.dirty = True
+
             data = self._execute("SELECT value FROM %s WHERE version=? AND pkgarch=? AND checksum=?;" % self.table,
                            (version, pkgarch, checksum))
             row = data.fetchone()
@@ -139,6 +151,8 @@ class PRTable(object):
             except sqlite3.IntegrityError as exc:
                 logger.error(str(exc))
 
+        self.dirty = True
+
         data = self._execute("SELECT value FROM %s WHERE version=? AND pkgarch=? AND checksum=? AND value>=?;" % self.table,
                             (version,pkgarch,checksum,value))
         row=data.fetchone()
diff --git a/lib/prserv/serv.py b/lib/prserv/serv.py
index 1b08d59..6ab1097 100644
--- a/lib/prserv/serv.py
+++ b/lib/prserv/serv.py
@@ -122,6 +122,10 @@ class PRServer(SimpleXMLRPCServer):
     def work_forever(self,):
         self.quit = False
         self.timeout = 0.5
+        iter_count = 1
+        # With 60 iterations between syncs and a 0.5 second timeout between
+        # iterations, this will sync if dirty every ~30 seconds.
+        iterations_between_sync = 60
 
         logger.info("Started PRServer with DBfile: %s, IP: %s, PORT: %s, PID: %s" %
                      (self.dbfile, self.host, self.port, str(os.getpid())))
@@ -129,6 +133,9 @@ class PRServer(SimpleXMLRPCServer):
         self.handlerthread.start()
         while not self.quit:
             self.handle_request()
+            iter_count = (iter_count + 1) % iterations_between_sync
+            if iter_count == 0:
+                self.table.sync_if_dirty()
 
         self.table.sync()
         logger.info("PRServer: stopping...")
-- 
2.1.1