14e02da475
APM integrations need to tag a span with the subject of the request, but the
user-defined `server_context` hash passed to `Server.new` never reaches
`around_request` or `instrumentation_callback`. The exception reporter's
`server_context` argument is a different value — it describes where a failure
occurred (`{ request: ... }`, `{ notification: ... }`), not who made the call —
so there is currently no way to read the request subject from a hook.
Add `Configuration#instrument_server_context`, off by default. When enabled,
`instrument_call` puts the host's `server_context` into the instrumentation data
before invoking `around_request`, so it is readable both before and after
`request_handler.call`.
The flag is opt-in rather than unconditional because the hash is
application-supplied and may hold values a tracing backend should not receive.
Hosts that do not expose a `server_context` reader are unaffected.
`instrument_call` reads it through `self.server_context`: the existing
`server_context:` keyword shadows the reader, and the value wanted here is the
user-defined hash, not the reporter context.
Follows the same shape as the earlier additions of `tool_arguments` (#218) and
`client` (#221) to this hash.
51 lines
1.9 KiB
Ruby
51 lines
1.9 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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# `self.` is required: the `server_context:` keyword above shadows the
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# reader, and the value we want here is the user-defined hash passed to
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# `Server.new`, not the per-call reporter context.
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if configuration.instrument_server_context? && respond_to?(:server_context)
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add_instrumentation_data(server_context: self.server_context)
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end
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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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rescue Exception
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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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