prserv: Add dump_db()

Returns a script (string) that reconstructs the state of the
entire database at the time this function is called. The script
language is defined by the backing database engine, which is a
function of server configuration.
Returns None if the database engine does not support dumping to
script or if some other error is encountered in processing.

The SQLite3 implementation in db.py calls iterdump() [1] to generate
a script. iterdump() is the library equivalent of the `sqlite3 .dump`
shell command, and the scripts are compatible. Execute the script in
an empty SQLite3 database using the sqlite3 utility to restore a backup
of prserv.

Use case: Backup a live PR server database in a non-racy way, such
that one could snapshot the entire database after a set of bitbake
builds all using a shared server. I.e. All changes made prior to
the start of a dump_db() operation should be committed and captured
in the script. Subsequent changes made during the backup process are
not guaranteed to be captured.

Testing: ~7MB database backs up in ~1s while PR server is under load
from 32 thread bitbake builds on two separate machines.

[1] https://docs.python.org/2/library/sqlite3.html#sqlite3.Connection.iterdump

Signed-off-by: Haris Okanovic <haris.okanovic@ni.com>
Reviewed-by: Ken Sharp <ken.sharp@ni.com>
Reviewed-by: Bill Pittman <bill.pittman@ni.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

diff --git a/lib/prserv/db.py b/lib/prserv/db.py
index 36c9f7b63084d526c7c423af2ec3c69f7c4eaa11..2a861841707781f8d1418932b5dc8af9c839fffb 100644 (file)
--- a/lib/prserv/db.py
+++ b/lib/prserv/db.py
@@ -231,6 +231,14 @@ class PRTable(object):
                 datainfo.append(col)
         return (metainfo, datainfo)
 
+    def dump_db(self, fd):
+        writeCount = 0
+        for line in self.conn.iterdump():
+            writeCount = writeCount + len(line) + 1
+            fd.write(line)
+            fd.write('\n')
+        return writeCount
+
 class PRData(object):
     """Object representing the PR database"""
     def __init__(self, filename, nohist=True):

diff --git a/lib/prserv/serv.py b/lib/prserv/serv.py
index f588f4dc27c1cfceb81e6ccf0c88361879fe6f40..affccd9b3b2733a17e9280324160ceb15d8ec1aa 100644 (file)
--- a/lib/prserv/serv.py
+++ b/lib/prserv/serv.py
@@ -4,6 +4,7 @@ from SimpleXMLRPCServer import SimpleXMLRPCServer, SimpleXMLRPCRequestHandler
 import threading
 import Queue
 import socket
+import StringIO
 
 try:
     import sqlite3
@@ -59,6 +60,7 @@ class PRServer(SimpleXMLRPCServer):
         self.register_function(self.quit, "quit")
         self.register_function(self.ping, "ping")
         self.register_function(self.export, "export")
+        self.register_function(self.dump_db, "dump_db")
         self.register_function(self.importone, "importone")
         self.register_introspection_functions()
 
@@ -115,6 +117,26 @@ class PRServer(SimpleXMLRPCServer):
             logger.error(str(exc))
             return None
 
+    def dump_db(self):
+        """
+        Returns a script (string) that reconstructs the state of the
+        entire database at the time this function is called. The script
+        language is defined by the backing database engine, which is a
+        function of server configuration.
+        Returns None if the database engine does not support dumping to
+        script or if some other error is encountered in processing.
+        """
+        buff = StringIO.StringIO()
+        try:
+            self.table.sync()
+            self.table.dump_db(buff)
+            return buff.getvalue()
+        except Exception as exc:
+            logger.error(str(exc))
+            return None
+        finally:
+            buff.close()
+
     def importone(self, version, pkgarch, checksum, value):
         return self.table.importone(version, pkgarch, checksum, value)
 
@@ -288,6 +310,9 @@ class PRServerConnection(object):
     def export(self,version=None, pkgarch=None, checksum=None, colinfo=True):
         return self.connection.export(version, pkgarch, checksum, colinfo)
 
+    def dump_db(self):
+        return self.connection.dump_db()
+
     def importone(self, version, pkgarch, checksum, value):
         return self.connection.importone(version, pkgarch, checksum, value)