View Source MnesiaAssistant (Mishka developer tools v0.1.7)
MnesiaAssistant
is a wrapper for the Mnesia (Top level Erlang runtime database, ETS) module.
Its primary purpose is to facilitate the utilisation of this database in Elixir.
Additionally, it offers a number of features, such as the standardisation of
the output and routes, as well as various hooks and helpers in this particular domain.
The following is a list of the primary modules that you plan on using in your project:
Summary
Functions
The :mnesia.change_config/2
function in Mnesia, the distributed database management
system in Erlang/OTP, is used to dynamically change the configuration parameters
of the Mnesia system while it is running.
When tracing a system of Mnesia applications it is useful to be able to
interleave Mnesia own events with application-related
events that give
information about the application context.
The mnesia
database provides you with the capability to perform your storage
either on the hard drive or on the RAM, or both at the same time, depending
on the software approach that you have chosen. In order to accomplish this goal,
its path for storage on the disc (the position of storage) must be known.
This can be accomplished in a number of different ways.
In order to fulfil the requirements of the Elixir project,
it is necessary for you to activate this database in
addition to executing the mnesia
function within the mix.exs
file.
Both activation and information for determining whether or not it is
active are accomplished through the utilisation of these functions.
Read start/0
document.
This function determines whether or not the mnesia
function is active.
The output of the Application.started_applications()
function
is what this function actually searches for.
You have the ability to disable mnesia by using the function.
In the same way that the start/0
function has two forms,
this function also has two forms. One of the forms is a wrapper
for the mnesia
function itself, while the other form disables
the mnesia
Elixir red applications that have been active.
Read stop/1
document.
Using this function, you will be able to subscribe to Mnesia's activities
and events, and you will receive notifications immediately after an
event takes place. For example, if you are using GenServer
and you want
to carry out a particular activity in real time based on a strategy, you can
make use of this method.
In order to terminate your subscription to mnesia, you can use the following function.
For more information read subscribe/1
Functions
The :mnesia.change_config/2
function in Mnesia, the distributed database management
system in Erlang/OTP, is used to dynamically change the configuration parameters
of the Mnesia system while it is running.
This function allows you to adjust certain operational parameters of Mnesia without needing to stop and restart the database, making it particularly useful for tuning performance or behavior in live systems.
config
: --> extra_db_nodes | dc_dump_limitvalue
: --> [node()] | number()
Example
MnesiaAssistant.change_config(config, value)
When tracing a system of Mnesia applications it is useful to be able to
interleave Mnesia own events with application-related
events that give
information about the application context.
Whenever the application begins a new and demanding Mnesia task,
or if it enters a new interesting phase in its execution, it can be a good idea
to use mnesia:report_event/1. Event can be any term and generates
a {mnesia_user, Event}
event for any processes that subscribe
to Mnesia system events. for more information read subscribe/1
document.
Example:
MnesiaAssistant.report_event(event)
The mnesia
database provides you with the capability to perform your storage
either on the hard drive or on the RAM, or both at the same time, depending
on the software approach that you have chosen. In order to accomplish this goal,
its path for storage on the disc (the position of storage) must be known.
This can be accomplished in a number of different ways.
You can begin the compilation process by using the configuration file of
your programme. In this technique, you will need to specify the directory
for the :mnesia
(:dir
) command. And then there is the second technique,
which is the function of the same function and is carried out in the form of run time.
Example
MnesiaAssistant.set_dir("/tmp/db") # --> Application.put_env(:mnesia, :dir, dir)
In order to fulfil the requirements of the Elixir project,
it is necessary for you to activate this database in
addition to executing the mnesia
function within the mix.exs
file.
Both activation and information for determining whether or not it is
active are accomplished through the utilisation of these functions.
Two distinct variants of this function have been generated for your use.
It is important to note that the start/0
function is a wrapper
from Erlang, while the second function is responsible for activating
mnesia
in Elixir (start/1
:: :app
).
In order to activate programmes, we utilise the
start/1
command with the input:app
.
Example
MnesiaAssistant.start() # --> :mnesia.start()
# OR
MnesiaAssistant.start(:app) # --> Application.start(:mnesia)
Read start/0
document.
This function determines whether or not the mnesia
function is active.
The output of the Application.started_applications()
function
is what this function actually searches for.
Example
MnesiaAssistant.started?()
You have the ability to disable mnesia by using the function.
In the same way that the start/0
function has two forms,
this function also has two forms. One of the forms is a wrapper
for the mnesia
function itself, while the other form disables
the mnesia
Elixir red applications that have been active.
Example
MnesiaAssistant.stop() # --> :mnesia.stop()
# OR
MnesiaAssistant.stop(:app) # --> Application.stop(:mnesia)
Read stop/1
document.
Using this function, you will be able to subscribe to Mnesia's activities
and events, and you will receive notifications immediately after an
event takes place. For example, if you are using GenServer
and you want
to carry out a particular activity in real time based on a strategy, you can
make use of this method.
Example
MnesiaAssistant.subscribe({:table, Person})
# -> :mnesia.subscribe({:table, table})
MnesiaAssistant.subscribe({:table, Person, simple_detailed})
# -> :mnesia.subscribe({:table, table, simple_detailed})
MnesiaAssistant.subscribe(what)
# -> :mnesia.subscribe(what)
# What = system | activity | {table, table(), simple | detailed}
In order to terminate your subscription to mnesia, you can use the following function.
For more information read subscribe/1
Example
MnesiaAssistant.unsubscribe({:table, Person})
# -> :mnesia.unsubscribe({:table, table})
MnesiaAssistant.unsubscribe({:table, Person, simple_detailed})
# -> :mnesia.unsubscribe({:table, table, simple_detailed})
MnesiaAssistant.unsubscribe(what)
# -> :mnesia.unsubscribe(what)
# What = system | activity | {table, table(), simple | detailed}