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-module(mongoose_backend). |
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%% API |
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-export([init/4, |
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call/4, |
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call_tracked/4, |
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is_exported/4, |
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get_backend_name/2]). |
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%% remove after mongoose_rdbms is refactored not to use dynamically compiled backend |
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-ignore_xref([get_backend_name/2]). |
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%% For debugging and tests |
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-export([get_backend_module/2]). |
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-ignore_xref([get_backend_module/2]). |
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-type function_name() :: atom(). |
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-type main_module() :: module(). |
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-type backend_module() :: module(). |
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-type host_type_or_global() :: mongooseim:host_type_or_global(). |
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-spec init(HostType :: host_type_or_global(), |
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MainModule :: main_module(), |
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TrackedFuns :: [function_name()], |
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Opts :: map()) -> ok. |
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init(HostType, MainModule, TrackedFuns, Opts) -> |
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Backend = maps:get(backend, Opts, mnesia), |
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BackendModule = backend_module(MainModule, Backend), |
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persist_backend_name(HostType, MainModule, Backend, BackendModule), |
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try |
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mongoose_instrument:set_up(instrumentation(HostType, BackendModule, TrackedFuns)) |
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catch error:#{what := event_already_registered} -> |
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%% The same backend can be initialized more than once because: |
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%% - either it is global, and a module initializes it for each host type |
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%% - or the module (or the entire app) was restarted |
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ok |
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end. |
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backend_module(Module, Backend) -> |
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list_to_atom(atom_to_list(Module) ++ "_" ++ atom_to_list(Backend)). |
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backend_key(HostType, MainModule) -> |
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{backend_module, HostType, MainModule}. |
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backend_name_key(HostType, MainModule) -> |
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{backend_name, HostType, MainModule}. |
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-spec instrumentation(host_type_or_global(), module(), [function_name()]) -> |
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[mongoose_instrument:spec()]. |
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instrumentation(HostType, BackendModule, FunNames) -> |
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[{BackendModule, labels(HostType, FunName), |
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#{metrics => #{count => spiral, time => histogram}}} || FunName <- FunNames]. |
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-spec labels(host_type_or_global(), function_name()) -> mongoose_instrument:labels(). |
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labels(global, FunName) -> |
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#{function => FunName}; |
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labels(HostType, FunName) -> |
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#{function => FunName, host_type => HostType}. |
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persist_backend_name(HostType, MainModule, Backend, BackendModule) -> |
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ModuleKey = backend_key(HostType, MainModule), |
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persistent_term:put(ModuleKey, BackendModule), |
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NameKey = backend_name_key(HostType, MainModule), |
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persistent_term:put(NameKey, Backend). |
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%% @doc Get a backend module, stored in init. |
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-spec get_backend_module(HostType :: host_type_or_global(), |
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MainModule :: main_module()) -> |
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BackendModule :: backend_module(). |
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get_backend_module(HostType, MainModule) -> |
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ModuleKey = backend_key(HostType, MainModule), |
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persistent_term:get(ModuleKey). |
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%% @doc Get a backend name, like `pgsql', stored in init. |
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-spec get_backend_name(HostType :: host_type_or_global(), |
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MainModule :: main_module()) -> BackendName :: atom(). |
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get_backend_name(HostType, MainModule) -> |
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Key = backend_name_key(HostType, MainModule), |
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persistent_term:get(Key). |
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-spec call(HostType :: host_type_or_global(), |
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MainModule :: main_module(), |
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FunName :: function_name(), |
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Args :: [term()]) -> term(). |
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call(HostType, MainModule, FunName, Args) -> |
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BackendModule = get_backend_module(HostType, MainModule), |
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erlang:apply(BackendModule, FunName, Args). |
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-spec call_tracked(HostType :: host_type_or_global(), |
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MainModule :: main_module(), |
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FunName :: function_name(), |
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Args :: [term()]) -> term(). |
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call_tracked(HostType, MainModule, FunName, Args) -> |
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BackendModule = get_backend_module(HostType, MainModule), |
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mongoose_instrument:span(BackendModule, labels(HostType, FunName), |
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BackendModule, FunName, Args, |
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fun(Time, _Result) -> #{args => Args, time => Time, count => 1} end). |
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-spec is_exported(HostType :: host_type_or_global(), |
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MainModule :: main_module(), |
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FunName :: function_name(), |
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Arity :: integer()) -> boolean(). |
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is_exported(HostType, MainModule, Function, Arity) -> |
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BackendModule = get_backend_module(HostType, MainModule), |
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erlang:function_exported(BackendModule, Function, Arity). |