trigger list, error.last, box.once

doc/sphinx/book/box/box_error.rst

@@ -62,10 +62,13 @@ be presented to the client as ``ER_PROC_LUA``.
 .. function:: box.error.last()
 
     Returns a description of the last error, as a Lua table
-    with three members: "type" (string) error's C++ class,
-    "message" (string) error's message, "code" (numeric) error's number.
+    with five members: "line" (number) Tarantool source file line number,
+    "code" (number) error's number,
+    "type", (string) error's C++ class,
+    "message" (string) error's message,
+    "file" (string) Tarantool source file.
     Additionally, if the error is a system error (for example due to a
-    failure in socket or file io), there is a fourth member:
+    failure in socket or file io), there may be a sixth member:
     "errno" (number) C standard error number.
 
     rtype: table
@@ -82,13 +85,18 @@ be presented to the client as ``ER_PROC_LUA``.
     | :codenormal:`- error: Arbitrary message`
     | :codenormal:`..`
     |
+    | :codenormal:`tarantool>` :codebold:`box.schema.space.create('#')`
+    | :codenormal:`---`
+    | :codenormal:`- error: Invalid identifier '#' (expected letters, digits or an underscore)`
+    | :codenormal:`...`
     | :codenormal:`tarantool>` :codebold:`box.error.last()`
     | :codenormal:`---`
-    | :codenormal:`- type: ClientError`
-    | :codenormal:`message: Arbitrary message`
-    | :codenormal:`code: 555`
+    | :codenormal:`- line: 278`
+    | |nbsp| |nbsp| :codenormal:`code: 70`
+    | |nbsp| |nbsp| :codenormal:`type: ClientError`
+    | |nbsp| |nbsp| :codenormal:`message: Invalid identifier '#' (expected letters, digits or an underscore)`
+    | |nbsp| |nbsp| :codenormal:`file: /tmp/buildd/tarantool-1.6.6.252.g1654e31~precise/src/box/key_def.cc`
     | :codenormal:`...`
-    |
     | :codenormal:`tarantool>` :codebold:`box.error.clear()`
     | :codenormal:`---`
     | :codenormal:`...`

doc/sphinx/book/box/triggers.rst

@@ -30,8 +30,8 @@ All triggers have the following characteristics.
   order that they were defined in.
 * They must work `within the event context`. If the function contains requests
   which normally could not occur immediately after the event but before the
-  return from the event, effects are undefined. For example, defining a trigger
-  function as ``os.exit()`` or ``box.rollback()`` would be bringing in requests
+  return from the event, effects are undefined. For example, putting
+  ``os.exit()`` or ``box.rollback()`` in a trigger function would be bringing in requests
   outside the event context.
 * They are `replaceable`. The request to "redefine a trigger" consists of passing
   the names of a new trigger function and an old trigger function to one of the
@@ -194,7 +194,7 @@ is executed once after each insert.
 
 The following series of requests will associate an existing function named F
 with an existing space named T, associate the function a second time with the
-same space (so it will be called twice), disable all triggers of T, and destroy
+same space (so it will be called twice), disable all triggers of T, and delete
 each trigger by replacing with ``nil``.
 
 .. code-block:: lua
@@ -210,14 +210,15 @@ each trigger by replacing with ``nil``.
 ===========================================================
 
 The code :code:`on_connect()` -- with no arguments --
-lists all connect-trigger functions;
-:code:`on_auth()` lists all authentication-trigger functions;
-:code:`on_disconnect()` lists all disconnect-trigger functions;
-:code:`on_replace()` lists all replace-trigger functions.
+returns a table of all connect-trigger functions;
+:code:`on_auth()` returns all authentication-trigger functions;
+:code:`on_disconnect()` returns all disconnect-trigger functions;
+:code:`on_replace()` returns all replace-trigger functions.
 In the following example a user finds that there are
 three functions associated with :code:`on_connect`
 triggers, and executes the third function, which happens to
 contain the line "print('function #3')".
+Then it deletes the third trigger.
 
   | :codenormal:`tarantool>` :codebold:`box.session.on_connect()`
   | :codenormal:`---`
@@ -230,6 +231,9 @@ contain the line "print('function #3')".
   | :codenormal:`function #3`
   | :codenormal:`---`
   | :codenormal:`...`
+  | :codenormal:`tarantool>` :codebold:`box.session.on_connect(nil,box.session.on_connect()[3])`
+  | :codenormal:`---`
+  | :codenormal:`...`
 
 
 

doc/sphinx/book/replication/index.rst

@@ -143,6 +143,26 @@ If a primary server is started with :codenormal:`box.cfg{...logger =` :codeitali
 then there will be lines in the log file, containing the word "relay",
 when a replica connects or disconnects.
 
+=====================================================================
+                    Preventing Duplicate Actions
+=====================================================================
+
+Suppose that the replica tries to do something
+that the master has already done. For example: |br|
+:code:`box.schema.space.create('X')` |br|
+This would cause an error, "Space X exists".
+For this particular situation, the code could be changed to: |br|
+:code:`box.schema.space.create('X',{if_not_exists=true})` |br|
+But there is a more general solution: the
+:samp:`box.once({key},{function})` method.
+If :code:`box.once()` has been called before with the
+same :codeitalic:`key` value, then :codeitalic:`function`
+is ignored; otherwise :codeitalic:`function` is executed.
+Therefore, actions which should only occur once during the
+life of a replicated session should be placed in a function
+which is executed via :code:`box.once()`. For example: |br|
+:codebold:`function f() box.schema.space.create('X'); end` |br|
+:codebold:`box.once('space_creator',f)`
 
 =====================================================================
                     Master-Master Replication