Merge pull request #203 from PolyJIT/b/fix-migration-if-not-owner

Provide sane error handling for SQLAlchemy errors

Former-commit-id: 39616d481f2f7a99ac0b297829de5967e7ccc756
Former-commit-id: 588d6cf42fca4987049cc2dcf702386ed682fa33 [formerly b3b116d482b4e0b1bd7d7cc1a547ec1378f5c02d] [formerly a68bc82f22ba4b13a139e5297f1ad08005bdef90 [formerly cc46ccdfdc8bc49cb50d8a2a33994afcf23d7256]]
Former-commit-id: 48b212d9203f835ee83ba407cc6467ecc2ea4522 [formerly 3ac13aa31022ce941721037fe24c6ebede1e7698]
Former-commit-id: 23fced2c96381839cb1d3acc02e4d3b835c56176

benchbuild/db/versions/001_Remove_RegressionTest_table.py

@@ -3,8 +3,10 @@
 
 This table can and should be reintroduced by an experiment that requires it.
 """
-from sqlalchemy import Table, Column, ForeignKey, Integer, String
-from benchbuild.utils.schema import metadata
+import sqlalchemy as sa
+from sqlalchemy import Column, ForeignKey, Integer, String, Table
+
+from benchbuild.utils.schema import exceptions, metadata
 
 META = metadata()
 REGRESSION = Table('regressions', META,
@@ -19,10 +21,25 @@
 
 
 def upgrade(migrate_engine):
-    META.bind = migrate_engine
-    REGRESSION.drop()
+    @exceptions(
+        error_is_fatal=False,
+        error_messages={
+            sa.exc.ProgrammingError:
+            "Removing table 'Regressions' failed. Please delete the table manually"
+        })
+    def do_upgrade():
+        META.bind = migrate_engine
+        REGRESSION.drop()
+
+    do_upgrade()
 
 
 def downgrade(migrate_engine):
-    META.bind = migrate_engine
-    REGRESSION.create()
+    @exceptions(error_messages={
+        sa.exc.ProgrammingError: "Adding table 'Regressions' failed."
+    })
+    def do_downgrade():
+        META.bind = migrate_engine
+        REGRESSION.create()
+
+    do_downgrade()

benchbuild/db/versions/002_Remove_GlobalConfig_table.py

@@ -3,8 +3,11 @@
 
 This table can and should be reintroduced by an experiment that requires it.
 """
-from sqlalchemy import Table, Column, ForeignKey, Integer, String
-from benchbuild.utils.schema import metadata, GUID
+
+import sqlalchemy as sa
+from sqlalchemy import Column, ForeignKey, String, Table
+
+from benchbuild.utils.schema import GUID, exceptions, metadata
 
 META = metadata()
 GLOBAL = Table('globalconfig', META,
@@ -19,10 +22,25 @@
 
 
 def upgrade(migrate_engine):
-    META.bind = migrate_engine
-    GLOBAL.drop()
+    @exceptions(
+        error_is_fatal=False,
+        error_messages={
+            sa.exc.ProgrammingError:
+            "Removing table 'globalconfig' failed. Please delete the table manually"
+        })
+    def do_upgrade():
+        META.bind = migrate_engine
+        GLOBAL.drop()
+
+    do_upgrade()
 
 
 def downgrade(migrate_engine):
-    META.bind = migrate_engine
-    GLOBAL.create()
+    @exceptions(error_messages={
+        sa.exc.ProgrammingError: "Adding table 'globalconfig' failed."
+    })
+    def do_downgrade():
+        META.bind = migrate_engine
+        GLOBAL.create()
+
+    do_downgrade()

benchbuild/db/versions/003_Unmanage_Events.py

@@ -8,7 +8,8 @@
 """
 from sqlalchemy import (MetaData, SmallInteger, BigInteger, Numeric, Table,
                         Column, ForeignKey, Integer, String)
-from benchbuild.utils.schema import Run, RunGroup, Project, Experiment
+import sqlalchemy as sa
+from benchbuild.utils.schema import exceptions
 
 META = MetaData()
 
@@ -33,5 +34,10 @@ def upgrade(migrate_engine):
 
 
 def downgrade(migrate_engine):
-    META.bind = migrate_engine
-    EVENTS.create(checkfirst=True)
+    @exceptions(error_messages={
+        sa.exc.ProgrammingError:
+        "Adding table 'benchbuild_events' failed."
+    })
+    def do_downgrade():
+        META.bind = migrate_engine
+        EVENTS.create()

benchbuild/utils/schema.py

@@ -21,6 +21,7 @@
 paths for you.
 """
 
+import functools
 import logging
 import sys
 import uuid
@@ -32,7 +33,7 @@
 from sqlalchemy.dialects.postgresql import UUID
 from sqlalchemy.ext.declarative import declarative_base
 from sqlalchemy.orm import sessionmaker
-from sqlalchemy.types import (CHAR, Float, TypeDecorator)
+from sqlalchemy.types import CHAR, Float, TypeDecorator
 
 import benchbuild.settings as settings
 import benchbuild.utils.user_interface as ui
@@ -46,6 +47,48 @@ def metadata():
     return BASE.metadata
 
 
+def exceptions(error_is_fatal=True, error_messages=None):
+    """
+    Handle SQLAlchemy exceptions in a sane way.
+
+    Args:
+        func: An arbitrary function to wrap.
+        error_is_fatal: Should we exit the program on exception?
+        reraise: Should we reraise the exception, after logging? Only makes sense
+            if error_is_fatal is False.
+        error_messages: A dictionary that assigns an exception class to a
+            customized error message.
+    """
+
+    def exception_decorator(func):
+        nonlocal error_messages
+
+        @functools.wraps(func)
+        def exc_wrapper(*args, **kwargs):
+            nonlocal error_messages
+            try:
+                result = func(*args, **kwargs)
+            except sa.exc.SQLAlchemyError as err:
+                result = None
+                details = None
+                err_type = err.__class__
+                if error_messages and err_type in error_messages:
+                    details = error_messages[err_type]
+                if details:
+                    LOG.error(details)
+                LOG.error("For developers: (%s) %s", err.__class__, str(err))
+                if error_is_fatal:
+                    sys.exit("Abort, SQL operation failed.")
+                if not ui.ask(
+                        "I can continue at your own risk, do you want that?"):
+                    raise err
+            return result
+
+        return exc_wrapper
+
+    return exception_decorator
+
+
 class GUID(TypeDecorator):
     """Platform-independent GUID type.
 
@@ -306,6 +349,11 @@ def get_version_data():
     return (connect_str, repo_url)
 
 
+@exceptions(
+    error_messages={
+        sa.exc.ProgrammingError:
+        "Could not enforce versioning. Are you allowed to modify the database?"
+    })
 def enforce_versioning(force=False):
     """Install versioning on the db."""
     connect_str, repo_url = get_version_data()
@@ -335,6 +383,12 @@ def setup_versioning():
     return (repo_version, db_version)
 
 
+@exceptions(
+    error_messages={
+        sa.exc.ProgrammingError:
+        "Update failed."
+        " Base schema version diverged from the expected structure."
+    })
 def maybe_update_db(repo_version, db_version):
     if db_version is None:
         return
@@ -349,6 +403,7 @@ def maybe_update_db(repo_version, db_version):
     if not ui.ask("Should I attempt to update your schema to version '{0}'?".
                   format(repo_version)):
         LOG.error("User declined schema upgrade.")
+        return
 
     connect_str = settings.CFG["db"]["connect_string"].value()
     repo_url = bbpath.template_path("../db/")
@@ -390,6 +445,10 @@ def configure_engine(self):
             LOG.warning("Unable to set isolation level to READ COMMITTED")
         return True
 
+    @exceptions(error_messages={
+        sa.exc.NoSuchModuleError:
+        "Connect string contained an invalid backend."
+    })
     def __init__(self):
         self.__test_mode = settings.CFG['db']['rollback'].value()
         self.engine = create_engine(