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a202f16100
* wip: observers * wip: float observers * fix copy pasta * wip: rework observers in sdk * small fix in global meter * wip: aggregators and selectors * wip: monotonicity option for observers * some refactor * wip: docs needs more package docs (especially for api/metric and sdk/metric) * fix ci * Fix copy-pasta in docs Co-Authored-By: Mauricio Vásquez <mauricio@kinvolk.io> * recycle unused recorders in observers if a recorder for a labelset is unused for a second collection cycle in a row, drop it * unregister * thread-safe set callback * Fix docs * Revert "wip: aggregators and selectors" This reverts commit 37b7d05aed5dc90f6d5593325b6eb77494e21736. * update selector * tests * Rework number equality Compare concrete numbers, so we can get actual numbers in the error message when they are not equal, not some uint64 representation. This also uses InDelta for comparing floats. * Ensure that Observers are registered in the same order * Run observers in fixed order So the tests can be reproducible - iterating a map made the order of measurements random. * Ensure the proper alignment of the delegates This wasn't checked at all. After adding the checks, the test-386 failed. * Small tweaks to the global meter test * Ensure proper alignment of the callback pointer test-386 was complaining about it * update docs * update a TODO * address review issues * drop SetCallback Co-authored-by: Mauricio Vásquez <mauricio@kinvolk.io> Co-authored-by: Rahul Patel <rghetia@yahoo.com>
85 lines
4.0 KiB
Go
85 lines
4.0 KiB
Go
// Copyright 2019, OpenTelemetry Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// metric package provides an API for reporting diagnostic
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// measurements using four basic kinds of instruments.
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//
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// The four basic kinds are:
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//
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// - counters
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// - gauges
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// - measures
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// - observers
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//
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// All instruments report either float64 or int64 values.
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//
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// The primary object that handles metrics is Meter. Meter can be
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// obtained from Provider. The implementations of the Meter and
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// Provider are provided by SDK. Normally, the Meter is used directly
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// only for the instrument creation, LabelSet generation and batch
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// recording.
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//
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// LabelSet is a set of keys and values that are in a suitable,
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// optimized form to be used by Meter.
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//
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// Counters are instruments that are reporting a quantity or a sum. An
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// example could be bank account balance or bytes downloaded. Counters
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// can be created with either NewFloat64Counter or
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// NewInt64Counter. Counters expect non-negative values by default to
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// be reported. This can be changed with the WithMonotonic option
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// (passing false as a parameter) passed to the Meter.New*Counter
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// function - this allows reporting negative values. To report the new
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// value, use an Add function.
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//
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// Gauges are instruments that are reporting a current state of a
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// value. An example could be voltage or temperature. Gauges can be
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// created with either NewFloat64Gauge or NewInt64Gauge. Gauges by
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// default have no limitations about reported values - they can be
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// less or greater than the last reported value. This can be changed
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// with the WithMonotonic option passed to the New*Gauge function -
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// this permits the reported values only to go up. To report a new
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// value, use the Set function.
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//
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// Measures are instruments that are reporting values that are
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// recorded separately to figure out some statistical properties from
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// those values (like average). An example could be temperature over
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// time or lines of code in the project over time. Measures can be
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// created with either NewFloat64Measure or NewInt64Measure. Measures
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// by default take only non-negative values. This can be changed with
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// the WithAbsolute option (passing false as a parameter) passed to
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// the New*Measure function - this allows reporting negative values
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// too. To report a new value, use the Record function.
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//
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// Observers are instruments that are reporting a current state of a
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// set of values. An example could be voltage or
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// temperature. Observers can be created with either
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// RegisterFloat64Observer or RegisterInt64Observer. Observers by
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// default have no limitations about reported values - they can be
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// less or greater than the last reported value. This can be changed
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// with the WithMonotonic option passed to the Register*Observer
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// function - this permits the reported values only to go
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// up. Reporting of the new values happens asynchronously, with the
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// use of a callback passed to the Register*Observer function. The
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// callback can report multiple values. To unregister the observer,
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// call Unregister on it.
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//
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// Counters, gauges and measures support creating bound instruments
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// for a potentially more efficient reporting. The bound instruments
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// have the same function names as the instruments (so a Counter bound
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// instrument has Add, a Gauge bound instrument has Set, and a Measure
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// bound instrument has Record). Bound Instruments can be created
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// with the Bind function of the respective instrument. When done with
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// the bound instrument, call Unbind on it.
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package metric // import "go.opentelemetry.io/otel/api/metric"
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