compiler_cache v1.2.1 CompilerCache behaviour
A callback-based compilation cache GenServer.
This genserver caches compiled expressions into a module.
While expressions are compiling (which can take some time), it returns values by calling Code.eval_quoted/3 which is more efficient in the short run.
Internally this uses a fixed pool of atoms as not to exhaust the atom table. A LRU cache mechanism is used to clean up unused expressions.
Example usage
defmodule MyExpressionParser do
use CompilerCache
def create_ast(expression) do
# Create your AST here based on the expression, e.g.:
{:ok, ast} = Code.string_to_quoted(expr)
{ast, []}
end
end
Configuration
In the use
statement it is possible to give extra compile-time
options to the compiler cache, like this:
use CompilerCache, [max_size: 1000, cache_misses: 0]
The possible options are:
input_name
- The name of the variable that’s being used for the input to the compiled function. Defaults toinput
.max_size
- how many entries we can have in the cache table; defaults to 10_000.cache_misses
- after how many cache misses the compiler should start compiling the module. Defaults to 1, which means that the first expression will not start compilation, but the second hit will. When specifying :none, no caching will be done. (for test purposes)max_ttl
- how long entries are allowed to linger in the cache (without being called), in seconds. Defaults to 10.
Summary
Functions
Returns a specification to start this module under a supervisor
Invoked when the server is started. start_link/3
or start/3
will
block until it returns
Callbacks
Create the Abstract Syntax Tree and the execution context for the given expression
Start the given compiler cache
Functions
Returns a specification to start this module under a supervisor.
See Supervisor
.
Invoked when the server is started. start_link/3
or start/3
will
block until it returns.
args
is the argument term (second argument) passed to start_link/3
.
Returning {:ok, state}
will cause start_link/3
to return
{:ok, pid}
and the process to enter its loop.
Returning {:ok, state, timeout}
is similar to {:ok, state}
except handle_info(:timeout, state)
will be called after timeout
milliseconds if no messages are received within the timeout.
Returning {:ok, state, :hibernate}
is similar to
{:ok, state}
except the process is hibernated before entering the loop. See
c:handle_call/3
for more information on hibernation.
Returning :ignore
will cause start_link/3
to return :ignore
and the
process will exit normally without entering the loop or calling c:terminate/2
.
If used when part of a supervision tree the parent supervisor will not fail
to start nor immediately try to restart the GenServer
. The remainder of the
supervision tree will be (re)started and so the GenServer
should not be
required by other processes. It can be started later with
Supervisor.restart_child/2
as the child specification is saved in the parent
supervisor. The main use cases for this are:
- The
GenServer
is disabled by configuration but might be enabled later. - An error occurred and it will be handled by a different mechanism than the
Supervisor
. Likely this approach involves callingSupervisor.restart_child/2
after a delay to attempt a restart.
Returning {:stop, reason}
will cause start_link/3
to return
{:error, reason}
and the process to exit with reason reason
without
entering the loop or calling c:terminate/2
.
Callback implementation for GenServer.init/1
.
Callbacks
Create the Abstract Syntax Tree and the execution context for the given expression.
Start the given compiler cache