This fix allows the gap detection and the writing of an IGNORABLE event
only if master_event_state == BLR_EVENT_DONE.
Note: The hole is not being created if the event is bigger than 16MB
When a connection to the master fails, readwritesplit should always treat
it the same way. Previously, if a connection to the master was lost but it
hadn't lost the master status, the failure would be treated like a slave
server failure.
When a server is created in server_create, it sets the port to the default
of 3306 if no explicit port is defined. The code that called this function
still expected a minimum of three arguments: name, address and port.
When a service is added or removed from a service, a supplementary
configuration file is created. This allows MaxScale to survive restars and
unexpected downtime even if runtime changes to the servers of a service
have been made.
With these changes, it is possible to start MaxScale without any servers,
create servers, add the created servers to services and monitors and
restart Maxscale without losing the runtime configuration changes.
When a server is added to a monitor, an supplementary configuration file
is generated to persist this information. This will allow dynamic
modifications to server lists which will survive restarts and unexpected
downtime.
The monitor will only add new servers to its list of monitored
servers. This prevents duplicate entries in the list and makes it safe to
persist all used servers to the supplementary configuration file instead of only the ones that are not listed in the main configuration.
Servers created at runtime can now be configured to use SSL. The
configuration is only possible if the server is not in use.
The `alter server` command in maxadmin now takes a list of `key=value`
strings. This allows the user to define multiple alter operations with one
command.
The backend references now use a common closing function so that all
variables are reset to proper states. The stored queries weren't always
freed and they would leak memory if left open.
Server creation and allocation are now the same apart from the fact that
allocation only adds the server to the running configuration where as the
creation of a server also persist it to disk.
The server serialization should not be seen through the server.h API. This
allows the serialization method to change without actually having to
change the interfaces.
When a server is created via MaxAdmin, it will be serialized to disk. This
allows created servers to be retained through a restart of MaxScale.
Currently, all serialized objects are stored in one folder and there is no
structure in the created files. In the future, servers could be created
under a `servers` subdirectory so that it is easier to see what was
added. Whether there is a need for this will be seen.
The address, port, monuser and monpw parameters of an existing server can
be changed at runtime. The support for enabling SSL will come in a later
commit.
Allowing servers to be modified could also be done by destroying and
recreating them. Since the servers are never actually destroyed, it is
better to allow the alteration of the existing ones.
The `add server` command accepts a server name and either a service name
or a monitor name. It will add servers to services and monitors. Since all
monitors use the MONITOR_SERVER structures directly, the monitors need
to be stopped before new servers are added to them
The debugcmd parameter processing didn't actually allow the maximum number
of parameters to be passed to the function. The detailed help text was
never printed and most of them were only duplicates of the short
description.
Before a query is routed to a backend, the status of the server reference
is checked. This allows the servers that are removed from a service to be
ejected from the list of active servers for active sessions.
The createInstace, newSession, closeSession and freeSession functions were
cleaned up and reorganized to be a bit clearer for the reader. Removed
unnecessary comments and replaced them with ones that explain what's
happening in the code.
Removed unused linked lists from both sessions and instances and replaced
them with better alternatives. This should improve performance since new
session don't have to acquire the instance level lock to put themselves
into the session list.
Removed the use of the BACKEND structure and replaced it with the use of
the SERVER_REF structure of the service. This allows dynamic changes to be
made to the list of servers.
Cleaned up parts of the code and removed obsolete or useless
functions. The schemarouter module could do with some refactoring since it
derives from readwritesplit.
The BACKEND structure in readconnroute is now replaced with the use of the
SERVER_REF structure of the service. This allows dynamic changes to the
list of servers to be made.
The readwritesplit now understands that the amount of servers can change
and some of the items in the list of server references aren't in use. This
allows dynamic changes to the number of servers used by readwritesplit.
Servers can now be added and removed from services which allows routers to
use them with new sessions. The routers don't fully use the new
functionality in the server references which prevents new servers from
being taken into use.
If shutdown has been initiated (via maxadmin or by sending a
SIGINT or SIGTERM) and a SIGTERM is received, the process
is terminated.
If shutdown has been initiated (via maxadmin or by sending a
SIGINT or SIGTERM) and a SIGINT (Ctrl-C) is received, a warning
is printed that shutdown is in progess. Then, if an additional
SIGINT is received, the process is terminated.
So, in practice:
- If MaxScale is running as a daemon, the first SIGTERM initiates
shutdown and a second one unconditionally terminates the process.
- If MaxScale is running in the console, the first Ctrl-C initiates
shutdown, the second prints a warning and the third terminates
the process.
This is to ensure that MaxScale can be forced to exit, in
case some thread is hung for whatever reason, and is thus preventing
the controlled shutdown.
The master reference used by the readwritesplit sessions needs to be
reassigned if slave reconnection occurs. This happens because the
reference refers to a certain place in the backend reference array
instead of the actual backend reference and those places are mixed
when the array is sorted.
The error logging is now more detailed and tells why the connection is
being closed. This should help the user figure out what is happening when
write fails and the connection is closed.
Some of the master server status checks didn't check whether the server
was actually running. The macros in server.h should always be used instead
of manually inspecting the server status.
If a readwritesplit session is active, it should never connect to a new
master. This will lead to unexpected results as the session states aren't
consistent.
If an illegal DCB close is done with a backend DCB, it will log the server
where it was connected. This allows us to know whether the DCB was
connected to a master or a slave.
Added more debug assertions to readwritesplit code. The DCBs should never
enter the DCB_STATE_DISCONNECTED.
Removed useless debug log messages. The messages usually just flood the
logs with no use to the developers.
