Move implementation(s) to there own sections

Instead of putting implementation(s) under the interfaces
section put the implementation(s) under there own section.

This also includes some other tweaks to refer to those
implementation(s) where appropriate.

Change-Id: Iffdc0439c843e7f70cf873e5a75501feb51f96c7

doc/source/conductors.rst

@@ -63,6 +63,10 @@ Interfaces
 ==========
 
 .. automodule:: taskflow.conductors.base
+
+Implementations
+===============
+
 .. automodule:: taskflow.conductors.single_threaded
 
 Hierarchy

doc/source/engines.rst

@@ -330,6 +330,11 @@ saved for this execution.
 Interfaces
 ==========
 
+.. automodule:: taskflow.engines.base
+
+Implementations
+===============
+
 .. automodule:: taskflow.engines.action_engine.analyzer
 .. automodule:: taskflow.engines.action_engine.compiler
 .. automodule:: taskflow.engines.action_engine.completer
@@ -339,7 +344,6 @@ Interfaces
 .. automodule:: taskflow.engines.action_engine.runtime
 .. automodule:: taskflow.engines.action_engine.scheduler
 .. automodule:: taskflow.engines.action_engine.scopes
-.. automodule:: taskflow.engines.base
 
 Hierarchy
 =========

doc/source/persistence.rst

@@ -155,6 +155,11 @@ Memory
 Retains all data in local memory (not persisted to reliable storage). Useful
 for scenarios where persistence is not required (and also in unit tests).
 
+.. note::
+
+    See :py:class:`~taskflow.persistence.backends.impl_memory.MemoryBackend`
+    for implementation details.
+
 Files
 -----
 
@@ -166,6 +171,11 @@ from the same local machine only). Useful for cases where a *more* reliable
 persistence is desired along with the simplicity of files and directories (a
 concept everyone is familiar with).
 
+.. note::
+
+    See :py:class:`~taskflow.persistence.backends.impl_dir.DirBackend`
+    for implementation details.
+
 Sqlalchemy
 ----------
 
@@ -228,6 +238,11 @@ parent_uuid  VARCHAR   False
 .. _sqlalchemy: http://www.sqlalchemy.org/docs/
 .. _ACID: https://en.wikipedia.org/wiki/ACID
 
+.. note::
+
+    See :py:class:`~taskflow.persistence.backends.impl_sqlalchemy.SQLAlchemyBackend`
+    for implementation details.
+
 Zookeeper
 ---------
 
@@ -241,6 +256,11 @@ logbook represented as znodes. Since zookeeper is also distributed it is also
 able to resume a engine from a peer machine (having similar functionality
 as the database connection types listed previously).
 
+.. note::
+
+    See :py:class:`~taskflow.persistence.backends.impl_zookeeper.ZkBackend`
+    for implementation details.
+
 .. _zookeeper: http://zookeeper.apache.org
 .. _kazoo: http://kazoo.readthedocs.org/
 
@@ -251,12 +271,21 @@ Interfaces
 .. automodule:: taskflow.persistence.backends.base
 .. automodule:: taskflow.persistence.logbook
 
+Implementations
+===============
+
+.. automodule:: taskflow.persistence.backends.impl_dir
+.. automodule:: taskflow.persistence.backends.impl_memory
+.. automodule:: taskflow.persistence.backends.impl_sqlalchemy
+.. automodule:: taskflow.persistence.backends.impl_zookeeper
+
 Hierarchy
 =========
 
 .. inheritance-diagram::
-    taskflow.persistence.backends.impl_memory
-    taskflow.persistence.backends.impl_zookeeper
+    taskflow.persistence.backends.base
     taskflow.persistence.backends.impl_dir
+    taskflow.persistence.backends.impl_memory
     taskflow.persistence.backends.impl_sqlalchemy
+    taskflow.persistence.backends.impl_zookeeper
     :parts: 2

taskflow/persistence/backends/impl_dir.py

@@ -46,11 +46,11 @@ class DirBackend(base.Backend):
     guarantee that there will be no interprocess race conditions when
     writing and reading by using a consistent hierarchy of file based locks.
 
-    Example conf:
+    Example configuration::
 
-    conf = {
-        "path": "/tmp/taskflow",
-    }
+        conf = {
+            "path": "/tmp/taskflow",
+        }
     """
     def __init__(self, conf):
         super(DirBackend, self).__init__(conf)

taskflow/persistence/backends/impl_sqlalchemy.py

@@ -183,11 +183,11 @@ def _ping_listener(dbapi_conn, connection_rec, connection_proxy):
 class SQLAlchemyBackend(base.Backend):
     """A sqlalchemy backend.
 
-    Example conf:
+    Example configuration::
 
-    conf = {
-        "connection": "sqlite:////tmp/test.db",
-    }
+        conf = {
+            "connection": "sqlite:////tmp/test.db",
+        }
     """
     def __init__(self, conf, engine=None):
         super(SQLAlchemyBackend, self).__init__(conf)

taskflow/persistence/backends/impl_zookeeper.py

@@ -43,12 +43,12 @@ class ZkBackend(base.Backend):
     inside those directories that represent the contents of those objects for
     later reading and writing.
 
-    Example conf:
+    Example configuration::
 
-    conf = {
-        "hosts": "192.168.0.1:2181,192.168.0.2:2181,192.168.0.3:2181",
-        "path": "/taskflow",
-    }
+        conf = {
+            "hosts": "192.168.0.1:2181,192.168.0.2:2181,192.168.0.3:2181",
+            "path": "/taskflow",
+        }
     """
     def __init__(self, conf, client=None):
         super(ZkBackend, self).__init__(conf)