defmodule Finch.Telemetry do
@moduledoc """
Telemetry integration.
Unless specified, all times are in `:native` units.
Finch executes the following events:
### Request Start
`[:finch, :request, :start]` - Executed when `Finch.request/3` or `Finch.stream/5` is called.
#### Measurements
* `:system_time` - The system time.
#### Metadata
* `:name` - The name of the Finch instance.
* `:request` - The request (`Finch.Request`).
### Request Stop
`[:finch, :request, :stop]` - Executed after `Finch.request/3` or `Finch.stream/5` ended.
#### Measurements
* `:duration` - Time taken from the request start event.
#### Metadata
* `:name` - The name of the Finch instance.
* `:request` - The request (`Finch.Request`).
* `:result` - The result of the operation. In case of `Finch.stream/5` this is
`{:ok, acc} | {:error, Exception.t()}`, where `acc` is the accumulator result of the
reducer passed in `Finch.stream/5`. In case of `Finch.request/3` this is
`{:ok, Finch.Response.t()} | {:error, Exception.t()}`.
### Request Exception
`[:finch, :request, :exception]` - Executed when an exception occurs while executing
`Finch.request/3` or `Finch.stream/5`.
#### Measurements
* `:duration` - The time it took since the start before raising the exception.
#### Metadata
* `:name` - The name of the Finch instance.
* `:request` - The request (`Finch.Request`).
* `:kind` - The type of exception.
* `:reason` - Error description or error data.
* `:stacktrace` - The stacktrace.
### Queue Start
`[:finch, :queue, :start]` - Executed before checking out a connection from the pool.
#### Measurements
* `:system_time` - The system time.
#### Metadata
* `:pool` - The pool's PID.
* `:request` - The request (`Finch.Request`).
### Queue Stop
`[:finch, :queue, :stop]` - Executed after a connection is retrieved from the pool.
#### Measurements
* `:duration` - Time taken to check out a pool connection.
* `:idle_time` - Elapsed time since the connection was last checked in or initialized.
#### Metadata
* `:pool` - The pool's PID.
* `:request` - The request (`Finch.Request`).
### Queue Exception
`[:finch, :queue, :exception]` - Executed if checking out a connection throws an exception.
#### Measurements
* `:duration` - The time it took since queue start event before raising an exception.
#### Metadata
* `:request` - The request (`Finch.Request`).
* `:kind` - The type of exception.
* `:reason` - Error description or error data.
* `:stacktrace` - The stacktrace.
### Connect Start
`[:finch, :connect, :start]` - Executed before opening a new connection.
If a connection is being re-used this event will *not* be executed.
#### Measurements
* `:system_time` - The system time.
#### Metadata
* `:scheme` - The scheme used in the connection. either `http` or `https`.
* `:host` - The host address.
* `:port` - The port to connect on.
### Connect Stop
`[:finch, :connect, :stop]` - Executed after a connection is opened.
#### Measurements
* `:duration` - Time taken to connect to the host.
#### Metadata
* `:scheme` - The scheme used in the connection. either `http` or `https`.
* `:host` - The host address.
* `:port` - The port to connect on.
* `:error` - This value is optional. It includes any errors that occurred while opening the connection.
### Send Start
`[:finch, :send, :start]` - Executed before sending a request.
#### Measurements
* `:system_time` - The system time.
* `:idle_time` - Elapsed time since the connection was last checked in or initialized.
#### Metadata
* `:request` - The request (`Finch.Request`).
### Send Stop
`[:finch, :send, :stop]` - Executed after a request is finished.
#### Measurements
* `:duration` - Time taken to make the request.
* `:idle_time` - Elapsed time since the connection was last checked in or initialized.
#### Metadata
* `:request` - The request (`Finch.Request`).
* `:error` - This value is optional. It includes any errors that occurred while making the request.
### Receive Start
`[:finch, :recv, :start]` - Executed before receiving the response.
#### Measurements
* `:system_time` - The system time.
* `:idle_time` - Elapsed time since the connection was last checked in or initialized.
#### Metadata
* `:request` - The request (`Finch.Request`).
### Receive Stop
`[:finch, :recv, :stop]` - Executed after a response has been fully received.
#### Measurements
* `:duration` - Duration to receive the response.
* `:idle_time` - Elapsed time since the connection was last checked in or initialized.
#### Metadata
* `:request` - The request (`Finch.Request`).
* `:status` - The response status (`Mint.Types.status()`).
* `:headers` - The response headers (`Mint.Types.headers()`).
* `:error` - This value is optional. It includes any errors that occurred while receiving the response.
### Receive Exception
`[:finch, :recv, :exception]` - Executed if an exception is thrown before the response has
been fully received.
#### Measurements
* `:duration` - The time it took before raising an exception
#### Metadata
* `:request` - The request (`Finch.Request`).
* `:kind` - The type of exception.
* `:reason` - Error description or error data.
* `:stacktrace` - The stacktrace.
### Reused Connection
`[:finch, :reused_connection]` - Executed if an existing connection is reused. There are no measurements provided with this event.
#### Metadata
* `:scheme` - The scheme used in the connection. either `http` or `https`.
* `:host` - The host address.
* `:port` - The port to connect on.
### Conn Max Idle Time Exceeded
`[:finch, :conn_max_idle_time_exceeded]` - Executed if a connection was discarded because the `conn_max_idle_time` had been reached.
#### Measurements
* `:idle_time` - Elapsed time since the connection was last checked in or initialized.
#### Metadata
* `:scheme` - The scheme used in the connection. either `http` or `https`.
* `:host` - The host address.
* `:port` - The port to connect on.
### Pool Max Idle Time Exceeded
`[:finch, :pool_max_idle_time_exceeded]` - Executed if a pool was terminated because the `pool_max_idle_time` has been reached. There are no measurements provided with this event.
#### Metadata
* `:scheme` - The scheme used in the connection. either `http` or `https`.
* `:host` - The host address.
* `:port` - The port to connect on.
### Max Idle Time Exceeded (Deprecated)
`[:finch, :max_idle_time_exceeded]` - Executed if a connection was discarded because the `max_idle_time` had been reached.
*Deprecated:* use `:conn_max_idle_time_exceeded` event instead.
#### Measurements
* `:idle_time` - Elapsed time since the connection was last checked in or initialized.
#### Metadata
* `:scheme` - The scheme used in the connection. either `http` or `https`.
* `:host` - The host address.
* `:port` - The port to connect on.
"""
@doc false
# emits a `start` telemetry event and returns the the start time
def start(event, meta \\ %{}, extra_measurements \\ %{}) do
start_time = System.monotonic_time()
:telemetry.execute(
[:finch, event, :start],
Map.merge(extra_measurements, %{system_time: System.system_time()}),
meta
)
start_time
end
@doc false
# Emits a stop event.
def stop(event, start_time, meta \\ %{}, extra_measurements \\ %{}) do
end_time = System.monotonic_time()
measurements = Map.merge(extra_measurements, %{duration: end_time - start_time})
:telemetry.execute(
[:finch, event, :stop],
measurements,
meta
)
end
@doc false
def exception(event, start_time, kind, reason, stack, meta \\ %{}, extra_measurements \\ %{}) do
end_time = System.monotonic_time()
measurements = Map.merge(extra_measurements, %{duration: end_time - start_time})
meta =
meta
|> Map.put(:kind, kind)
|> Map.put(:reason, reason)
|> Map.put(:stacktrace, stack)
:telemetry.execute([:finch, event, :exception], measurements, meta)
end
@doc false
# Used for reporting generic events
def event(event, measurements, meta) do
:telemetry.execute([:finch, event], measurements, meta)
end
@doc false
# Used to easily create :start, :stop, :exception events.
def span(event, start_metadata, fun) do
:telemetry.span(
[:finch, event],
start_metadata,
fun
)
end
end
