Initial commit: OCA Technical packages (595 packages)

odoo-bringout-oca-connector-connector/connector/database.py

@@ -0,0 +1,78 @@
+# Copyright 2013 Camptocamp SA
+# License LGPL-3.0 or later (http://www.gnu.org/licenses/lgpl.html)
+
+import hashlib
+import logging
+import struct
+
+_logger = logging.getLogger(__name__)
+
+
+def pg_try_advisory_lock(env, lock):
+    """Try to acquire a Postgres transactional advisory lock.
+
+    The function tries to acquire a lock, returns a boolean indicating
+    if it could be obtained or not. An acquired lock is released at the
+    end of the transaction.
+
+    A typical use is to acquire a lock at the beginning of an importer
+    to prevent 2 jobs to do the same import at the same time. Since the
+    record doesn't exist yet, we can't put a lock on a record, so we put
+    an advisory lock.
+
+    Example:
+     - Job 1 imports Partner A
+     - Job 2 imports Partner B
+     - Partner A has a category X which happens not to exist yet
+     - Partner B has a category X which happens not to exist yet
+     - Job 1 import category X as a dependency
+     - Job 2 import category X as a dependency
+
+    Since both jobs are executed concurrently, they both create a record
+    for category X so we have duplicated records.  With this lock:
+
+     - Job 1 imports Partner A, it acquires a lock for this partner
+     - Job 2 imports Partner B, it acquires a lock for this partner
+     - Partner A has a category X which happens not to exist yet
+     - Partner B has a category X which happens not to exist yet
+     - Job 1 import category X as a dependency, it acquires a lock for
+       this category
+     - Job 2 import category X as a dependency, try to acquire a lock
+       but can't, Job 2 is retried later, and when it is retried, it
+       sees the category X created by Job 1.
+
+    The lock is acquired until the end of the transaction.
+
+    Usage example:
+
+    ::
+
+        lock_name = 'import_record({}, {}, {}, {})'.format(
+            self.backend_record._name,
+            self.backend_record.id,
+            self.model._name,
+            self.external_id,
+        )
+        if pg_try_advisory_lock(lock_name):
+            # do sync
+        else:
+            raise RetryableJobError('Could not acquire advisory lock',
+                                    seconds=2,
+                                    ignore_retry=True)
+
+    :param env: the Odoo Environment
+    :param lock: The lock name. Can be anything convertible to a
+       string.  It needs to represents what should not be synchronized
+       concurrently so usually the string will contain at least: the
+       action, the backend type, the backend id, the model name, the
+       external id
+    :return True/False whether lock was acquired.
+    """
+    hasher = hashlib.sha1(str(lock).encode())
+    # pg_lock accepts an int8 so we build an hash composed with
+    # contextual information and we throw away some bits
+    int_lock = struct.unpack("q", hasher.digest()[:8])
+
+    env.cr.execute("SELECT pg_try_advisory_xact_lock(%s);", (int_lock,))
+    acquired = env.cr.fetchone()[0]
+    return acquired