fab6f81261
## Motivation and Context
`instrumentation_callback` fires after request execution, making it impossible to wrap
requests with Application Performance Monitoring (APM) spans (e.g. Datadog tracing).
This adds `around_request`, which wraps request handling and allows executing code
before and after each request.
For example, to wrap requests with a Datadog trace:
```ruby
MCP.configure do |config|
config.around_request = ->(data, &request_handler) {
Datadog::Tracing.trace("mcp.#{data[:method]}") do
request_handler.call
end
}
end
```
`instrumentation_callback` is soft-deprecated in favor of `around_request`.
## How Has This Been Tested?
Added tests for `around_request` in configuration, instrumentation,
and server test files. All existing tests continue to pass.
## Breaking Changes
`around_request` itself is optional and defaults to a pass-through,
and `instrumentation_callback` continues to work as before.
However, `instrument_call` now accepts a `server_context:` keyword and its block is invoked
without arguments (previously `yield block` passed the block Proc as an argument).
This affects anyone mixing `MCP::Instrumentation` into their own classes,
though the public `Server` API is unchanged.
Resolves #302.
47 lines
1.7 KiB
Ruby
47 lines
1.7 KiB
Ruby
# frozen_string_literal: true
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module MCP
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module Instrumentation
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def instrument_call(method, server_context: {}, exception_already_reported: nil, &block)
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start_time = Process.clock_gettime(Process::CLOCK_MONOTONIC)
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begin
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@instrumentation_data = {}
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add_instrumentation_data(method: method)
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result = configuration.around_request.call(@instrumentation_data, &block)
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result
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rescue => e
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already_reported = begin
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!!exception_already_reported&.call(e)
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# rubocop:disable Lint/RescueException
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rescue Exception
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# rubocop:enable Lint/RescueException
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# The predicate is expected to be side-effect-free and return a boolean.
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# Any exception raised from it (including non-StandardError such as SystemExit)
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# must not shadow the original exception.
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false
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end
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unless already_reported
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add_instrumentation_data(error: :internal_error) unless @instrumentation_data.key?(:error)
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configuration.exception_reporter.call(e, server_context)
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end
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raise
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ensure
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end_time = Process.clock_gettime(Process::CLOCK_MONOTONIC)
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add_instrumentation_data(duration: end_time - start_time)
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# Backward compatibility: `instrumentation_callback` is soft-deprecated
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# in favor of `around_request`, but existing callers still expect it
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# to fire after every request until it is removed in a future version.
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configuration.instrumentation_callback.call(@instrumentation_data)
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end
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end
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def add_instrumentation_data(**kwargs)
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@instrumentation_data.merge!(kwargs)
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end
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end
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end
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