Rework the persist_data API

Rather than having to run .addDomain() and then .getValue(domain, key),
.setValue(domain, key), etc, now it just works as mappings.

As an example:

    setValue(domain, key) -> persist[domain][key] = value

It also arranges things so we can construct objects of this type using any
arbitrary filename/path for the sqlite3 database, rather than being so
tightly bound to the metadata.

(Bitbake rev: d9e8b8af308ae871efdc8ef0782be30af8c1f894)

Signed-off-by: Chris Larson <chris_larson@mentor.com>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>

1 files changed, 137 insertions, 72 deletions

diff --git a/bitbake/lib/bb/persist_data.py b/bitbake/lib/bb/persist_data.py
index 9558e7128..4f87c37f2 100644
--- a/bitbake/lib/bb/persist_data.py
+++ b/bitbake/lib/bb/persist_data.py
@@ -1,6 +1,12 @@
-# BitBake Persistent Data Store
-#
+"""BitBake Persistent Data Store
+
+Used to store data in a central location such that other threads/tasks can
+access them at some future date.  Acts as a convenience wrapper around sqlite,
+currently, providing a key/value store accessed by 'domain'.
+"""
+
 # Copyright (C) 2007        Richard Purdie
+# Copyright (C) 2010        Chris Larson <chris_larson@mentor.com>
 #
 # This program is free software; you can redistribute it and/or modify
 # it under the terms of the GNU General Public License version 2 as
@@ -15,116 +21,175 @@
 # with this program; if not, write to the Free Software Foundation, Inc.,
 # 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 
-import os
+import collections
 import logging
-import bb
-import bb.utils
-
-logger = logging.getLogger("BitBake.PersistData")
+import os.path
+import sys
+import warnings
+import bb.msg, bb.data, bb.utils
 
 try:
     import sqlite3
 except ImportError:
-    try:
-        from pysqlite2 import dbapi2 as sqlite3
-    except ImportError:
-        bb.msg.fatal(bb.msg.domain.PersistData, "Importing sqlite3 and pysqlite2 failed, please install one of them. Python 2.5 or a 'python-pysqlite2' like package is likely to be what you need.")
+    from pysqlite2 import dbapi2 as sqlite3
 
 sqlversion = sqlite3.sqlite_version_info
 if sqlversion[0] < 3 or (sqlversion[0] == 3 and sqlversion[1] < 3):
-    bb.msg.fatal(bb.msg.domain.PersistData, "sqlite3 version 3.3.0 or later is required.")
+    raise Exception("sqlite3 version 3.3.0 or later is required.")
 
-class PersistData:
-    """
-    BitBake Persistent Data Store
 
-    Used to store data in a central location such that other threads/tasks can
-    access them at some future date.
+logger = logging.getLogger("BitBake.PersistData")
 
-    The "domain" is used as a key to isolate each data pool and in this
-    implementation corresponds to an SQL table. The SQL table consists of a
-    simple key and value pair.
 
-    Why sqlite? It handles all the locking issues for us.
-    """
-    def __init__(self, d):
-        self.cachedir = bb.data.getVar("PERSISTENT_DIR", d, True) or bb.data.getVar("CACHE", d, True)
-        if self.cachedir in [None, '']:
-            bb.msg.fatal(bb.msg.domain.PersistData, "Please set the 'PERSISTENT_DIR' or 'CACHE' variable.")
-        try:
-            os.stat(self.cachedir)
-        except OSError:
-            bb.utils.mkdirhier(self.cachedir)
+class SQLTable(collections.MutableMapping):
+    """Object representing a table/domain in the database"""
+    def __init__(self, cursor, table):
+        self.cursor = cursor
+        self.table = table
+
+        cursor.execute("CREATE TABLE IF NOT EXISTS %s(key TEXT, value TEXT);"
+                       % table)
+
+    def _execute(self, *query):
+        """Execute a query, waiting to acquire a lock if necessary"""
+        count = 0
+        while True:
+            try:
+                return self.cursor.execute(*query)
+                break
+            except sqlite3.OperationalError as exc:
+                if 'database is locked' in str(exc) and count < 500:
+                    count = count + 1
+                    continue
+                raise
+
+    def __getitem__(self, key):
+        data = self.cursor.execute("SELECT * from %s where key=?;" %
+                                   self.table, [key])
+        for row in data:
+            return row[1]
+
+    def __delitem__(self, key):
+        self._execute("DELETE from %s where key=?;" % self.table, [key])
+
+    def __setitem__(self, key, value):
+        data = self.cursor.execute("SELECT * from %s where key=?;" %
+                                   self.table, [key])
+        exists = len(list(data))
+        if exists:
+            self._execute("UPDATE %s SET value=? WHERE key=?;" % self.table,
+                          [value, key])
+        else:
+            self._execute("INSERT into %s(key, value) values (?, ?);" %
+                          self.table, [key, value])
+
+    def __contains__(self, key):
+        return key in set(self)
+
+    def __len__(self):
+        data = self.cursor.execute("SELECT COUNT(key) FROM %s;" % self.table)
+        for row in data:
+            return row[0]
+
+    def __iter__(self):
+        data = self.cursor.execute("SELECT key FROM %s;" % self.table)
+        for row in data:
+            yield row[0]
+
+    def iteritems(self):
+        data = self.cursor.execute("SELECT * FROM %s;" % self.table)
+        for row in data:
+            yield row[0], row[1]
+
+    def itervalues(self):
+        data = self.cursor.execute("SELECT value FROM %s;" % self.table)
+        for row in data:
+            yield row[0]
+
+
+class SQLData(object):
+    """Object representing the persistent data"""
+    def __init__(self, filename):
+        bb.utils.mkdirhier(os.path.dirname(filename))
+
+        self.filename = filename
+        self.connection = sqlite3.connect(filename, timeout=5,
+                                          isolation_level=None)
+        self.cursor = self.connection.cursor()
+        self._tables = {}
+
+    def __getitem__(self, table):
+        if not isinstance(table, basestring):
+            raise TypeError("table argument must be a string, not '%s'" %
+                            type(table))
 
-        self.cachefile = os.path.join(self.cachedir, "bb_persist_data.sqlite3")
-        logger.debug(1, "Using '%s' as the persistent data cache", self.cachefile)
+        if table in self._tables:
+            return self._tables[table]
+        else:
+            tableobj = self._tables[table] = SQLTable(self.cursor, table)
+            return tableobj
+
+    def __delitem__(self, table):
+        if table in self._tables:
+            del self._tables[table]
+        self.cursor.execute("DROP TABLE IF EXISTS %s;" % table)
 
-        self.connection = sqlite3.connect(self.cachefile, timeout=5, isolation_level=None)
+
+class PersistData(object):
+    """Deprecated representation of the bitbake persistent data store"""
+    def __init__(self, d):
+        warnings.warn("Use of PersistData will be deprecated in the future",
+                      category=PendingDeprecationWarning,
+                      stacklevel=2)
+
+        self.data = persist(d)
+        logger.debug(1, "Using '%s' as the persistent data cache",
+                     self.data.filename)
 
     def addDomain(self, domain):
         """
-        Should be called before any domain is used
-        Creates it if it doesn't exist.
+        Add a domain (pending deprecation)
         """
-        self._execute("CREATE TABLE IF NOT EXISTS %s(key TEXT, value TEXT);" % domain)
+        return self.data[domain]
 
     def delDomain(self, domain):
         """
         Removes a domain and all the data it contains
         """
-        self._execute("DROP TABLE IF EXISTS %s;" % domain)
+        del self.data[domain]
 
     def getKeyValues(self, domain):
         """
         Return a list of key + value pairs for a domain
         """
-        ret = {}
-        data = self._execute("SELECT key, value from %s;" % domain)
-        for row in data:
-            ret[str(row[0])] = str(row[1])
-
-        return ret
+        return self.data[domain].items()
 
     def getValue(self, domain, key):
         """
         Return the value of a key for a domain
         """
-        data = self._execute("SELECT * from %s where key=?;" % domain, [key])
-        for row in data:
-            return row[1]
+        return self.data[domain][key]
 
     def setValue(self, domain, key, value):
         """
         Sets the value of a key for a domain
         """
-        data = self._execute("SELECT * from %s where key=?;" % domain, [key])
-        rows = 0
-        for row in data:
-            rows = rows + 1
-        if rows:
-            self._execute("UPDATE %s SET value=? WHERE key=?;" % domain, [value, key])
-        else:
-            self._execute("INSERT into %s(key, value) values (?, ?);" % domain, [key, value])
+        self.data[domain][key] = value
 
     def delValue(self, domain, key):
         """
         Deletes a key/value pair
         """
-        self._execute("DELETE from %s where key=?;" % domain, [key])
-
-    #
-    # We wrap the sqlite execute calls as on contended machines or single threaded 
-    # systems we can have multiple processes trying to access the DB at once and it seems
-    # sqlite sometimes doesn't wait for the timeout. We therefore loop but put in an 
-    # emergency brake too
-    #
-    def _execute(self, *query):
-        count = 0
-        while True:
-            try:
-                return self.connection.execute(*query)
-            except sqlite3.OperationalError as e:
-                if 'database is locked' in str(e) and count < 500:
-                    count = count + 1
-                    continue
-                raise
+        del self.data[domain][key]
+
+
+def persist(d):
+    """Convenience factory for construction of SQLData based upon metadata"""
+    cachedir = (bb.data.getVar("PERSISTENT_DIR", d, True) or
+                bb.data.getVar("CACHE", d, True))
+    if not cachedir:
+        logger.critical("Please set the 'PERSISTENT_DIR' or 'CACHE' variable")
+        sys.exit(1)
+
+    cachefile = os.path.join(cachedir, "bb_persist_data.sqlite3")
+    return SQLData(cachefile)