From f6671ddd796570d737e7d6e5d362a58c2faec9e0 Mon Sep 17 00:00:00 2001
From: Tobias Bachert <git@b-privat.de>
Date: Sun, 16 Oct 2022 23:57:57 +0200
Subject: [PATCH] Add alternative instrumentation abstraction (#822)

* Add alternative instrumentation abstraction
* Provide global access to providers
Remove logs for now, will be replaced with `LoggerProvider` in the future.
---
 .../Instrumentation/CachedInstrumentation.php | 81 +++++++++++++++++
 .../Common/Instrumentation/Configurator.php   | 80 ++++++++++++++++
 .../Common/Instrumentation/ContextKeys.php    | 47 ++++++++++
 src/API/Common/Instrumentation/Globals.php    | 40 ++++++++
 .../Instrumentation/InstrumentationTest.php   | 91 +++++++++++++++++++
 5 files changed, 339 insertions(+)
 create mode 100644 src/API/Common/Instrumentation/CachedInstrumentation.php
 create mode 100644 src/API/Common/Instrumentation/Configurator.php
 create mode 100644 src/API/Common/Instrumentation/ContextKeys.php
 create mode 100644 src/API/Common/Instrumentation/Globals.php
 create mode 100644 tests/Unit/API/Common/Instrumentation/InstrumentationTest.php

diff --git a/src/API/Common/Instrumentation/CachedInstrumentation.php b/src/API/Common/Instrumentation/CachedInstrumentation.php
new file mode 100644
index 000000000..8bd0de592
--- /dev/null
+++ b/src/API/Common/Instrumentation/CachedInstrumentation.php
@@ -0,0 +1,81 @@
+<?php
+
+declare(strict_types=1);
+
+namespace OpenTelemetry\API\Common\Instrumentation;
+
+use ArrayAccess;
+use function assert;
+use function class_exists;
+use OpenTelemetry\API\Metrics\MeterInterface;
+use OpenTelemetry\API\Metrics\MeterProviderInterface;
+use OpenTelemetry\API\Trace\TracerInterface;
+use OpenTelemetry\API\Trace\TracerProviderInterface;
+use const PHP_VERSION_ID;
+
+/**
+ * Provides access to cached {@link TracerInterface} and {@link MeterInterface}
+ * instances.
+ *
+ * Autoinstrumentation should prefer using a {@link CachedInstrumentation}
+ * instance over repeatedly obtaining instrumentation instances from
+ * {@link Globals}.
+ */
+final class CachedInstrumentation
+{
+    private string $name;
+    private ?string $version;
+    private ?string $schemaUrl;
+    private iterable $attributes;
+    /** @var ArrayAccess<TracerProviderInterface, TracerInterface>|null */
+    private ?ArrayAccess $tracers;
+    /** @var ArrayAccess<MeterProviderInterface, MeterInterface>|null */
+    private ?ArrayAccess $meters;
+
+    public function __construct(string $name, ?string $version = null, ?string $schemaUrl = null, iterable $attributes = [])
+    {
+        $this->name = $name;
+        $this->version = $version;
+        $this->schemaUrl = $schemaUrl;
+        $this->attributes = $attributes;
+        $this->tracers = self::createWeakMap();
+        $this->meters = self::createWeakMap();
+    }
+
+    private static function createWeakMap(): ?ArrayAccess
+    {
+        if (PHP_VERSION_ID < 80000) {
+            return null;
+        }
+
+        /** @phan-suppress-next-line PhanUndeclaredClassReference */
+        assert(class_exists(\WeakMap::class, false));
+        /** @phan-suppress-next-line PhanUndeclaredClassMethod */
+        $map = new \WeakMap();
+        assert($map instanceof ArrayAccess);
+
+        return $map;
+    }
+
+    public function tracer(): TracerInterface
+    {
+        $tracerProvider = Globals::tracerProvider();
+
+        if ($this->tracers === null) {
+            return $tracerProvider->getTracer($this->name, $this->version, $this->schemaUrl, $this->attributes);
+        }
+
+        return $this->tracers[$tracerProvider] ??= $tracerProvider->getTracer($this->name, $this->version, $this->schemaUrl, $this->attributes);
+    }
+
+    public function meter(): MeterInterface
+    {
+        $meterProvider = Globals::meterProvider();
+
+        if ($this->meters === null) {
+            return $meterProvider->getMeter($this->name, $this->version, $this->schemaUrl, $this->attributes);
+        }
+
+        return $this->meters[$meterProvider] ??= $meterProvider->getMeter($this->name, $this->version, $this->schemaUrl, $this->attributes);
+    }
+}
diff --git a/src/API/Common/Instrumentation/Configurator.php b/src/API/Common/Instrumentation/Configurator.php
new file mode 100644
index 000000000..e34cd5eea
--- /dev/null
+++ b/src/API/Common/Instrumentation/Configurator.php
@@ -0,0 +1,80 @@
+<?php
+
+declare(strict_types=1);
+
+namespace OpenTelemetry\API\Common\Instrumentation;
+
+use OpenTelemetry\API\Metrics\MeterProviderInterface;
+use OpenTelemetry\API\Trace\TracerProviderInterface;
+use OpenTelemetry\Context\Context;
+use OpenTelemetry\Context\ContextInterface;
+use OpenTelemetry\Context\ImplicitContextKeyedInterface;
+use OpenTelemetry\Context\Propagation\TextMapPropagatorInterface;
+use OpenTelemetry\Context\ScopeInterface;
+
+/**
+ * Configures the global (context scoped) instrumentation instances.
+ *
+ * @see Configurator::activate()
+ */
+final class Configurator implements ImplicitContextKeyedInterface
+{
+    private ?TracerProviderInterface $tracerProvider = null;
+    private ?MeterProviderInterface $meterProvider = null;
+    private ?TextMapPropagatorInterface $propagator = null;
+
+    private function __construct()
+    {
+    }
+
+    public static function create(): Configurator
+    {
+        return new self();
+    }
+
+    public function activate(): ScopeInterface
+    {
+        return $this->storeInContext()->activate();
+    }
+
+    public function storeInContext(?ContextInterface $context = null): ContextInterface
+    {
+        $context ??= Context::getCurrent();
+
+        if ($this->tracerProvider !== null) {
+            $context = $context->with(ContextKeys::tracerProvider(), $this->tracerProvider);
+        }
+        if ($this->meterProvider !== null) {
+            $context = $context->with(ContextKeys::meterProvider(), $this->meterProvider);
+        }
+        if ($this->propagator !== null) {
+            $context = $context->with(ContextKeys::propagator(), $this->propagator);
+        }
+
+        return $context;
+    }
+
+    public function withTracerProvider(?TracerProviderInterface $tracerProvider): Configurator
+    {
+        $self = clone $this;
+        $self->tracerProvider = $tracerProvider;
+
+        return $self;
+    }
+
+    public function withMeterProvider(?MeterProviderInterface $meterProvider): Configurator
+    {
+        $self = clone $this;
+        $self->meterProvider = $meterProvider;
+
+        return $self;
+    }
+
+    public function withPropagator(?TextMapPropagatorInterface $propagator): Configurator
+    {
+        $self = clone $this;
+        $self->propagator = $propagator;
+
+        return $self;
+    }
+}
diff --git a/src/API/Common/Instrumentation/ContextKeys.php b/src/API/Common/Instrumentation/ContextKeys.php
new file mode 100644
index 000000000..590a75d41
--- /dev/null
+++ b/src/API/Common/Instrumentation/ContextKeys.php
@@ -0,0 +1,47 @@
+<?php
+
+declare(strict_types=1);
+
+namespace OpenTelemetry\API\Common\Instrumentation;
+
+use OpenTelemetry\API\Metrics\MeterProviderInterface;
+use OpenTelemetry\API\Trace\TracerProviderInterface;
+use OpenTelemetry\Context\Context;
+use OpenTelemetry\Context\ContextKeyInterface;
+use OpenTelemetry\Context\Propagation\TextMapPropagatorInterface;
+
+/**
+ * @internal
+ */
+final class ContextKeys
+{
+    /**
+     * @return ContextKeyInterface<TracerProviderInterface>
+     */
+    public static function tracerProvider(): ContextKeyInterface
+    {
+        static $instance;
+
+        return $instance ??= Context::createKey(TracerProviderInterface::class);
+    }
+
+    /**
+     * @return ContextKeyInterface<MeterProviderInterface>
+     */
+    public static function meterProvider(): ContextKeyInterface
+    {
+        static $instance;
+
+        return $instance ??= Context::createKey(MeterProviderInterface::class);
+    }
+
+    /**
+     * @return ContextKeyInterface<TextMapPropagatorInterface>
+     */
+    public static function propagator(): ContextKeyInterface
+    {
+        static $instance;
+
+        return $instance ??= Context::createKey(TextMapPropagatorInterface::class);
+    }
+}
diff --git a/src/API/Common/Instrumentation/Globals.php b/src/API/Common/Instrumentation/Globals.php
new file mode 100644
index 000000000..6c35133e7
--- /dev/null
+++ b/src/API/Common/Instrumentation/Globals.php
@@ -0,0 +1,40 @@
+<?php
+
+declare(strict_types=1);
+
+namespace OpenTelemetry\API\Common\Instrumentation;
+
+use OpenTelemetry\API\Metrics\MeterProviderInterface;
+use OpenTelemetry\API\Metrics\Noop\NoopMeterProvider;
+use OpenTelemetry\API\Trace\NoopTracerProvider;
+use OpenTelemetry\API\Trace\TracerProviderInterface;
+use OpenTelemetry\Context\Context;
+use OpenTelemetry\Context\Propagation\NoopTextMapPropagator;
+use OpenTelemetry\Context\Propagation\TextMapPropagatorInterface;
+
+/**
+ * Provides access to the globally configured instrumentation instances.
+ */
+final class Globals
+{
+    public static function tracerProvider(): TracerProviderInterface
+    {
+        static $noop;
+
+        return Context::getCurrent()->get(ContextKeys::tracerProvider()) ?? $noop ??= new NoopTracerProvider();
+    }
+
+    public static function meterProvider(): MeterProviderInterface
+    {
+        static $noop;
+
+        return Context::getCurrent()->get(ContextKeys::meterProvider()) ?? $noop ??= new NoopMeterProvider();
+    }
+
+    public static function propagator(): TextMapPropagatorInterface
+    {
+        static $noop;
+
+        return Context::getCurrent()->get(ContextKeys::propagator()) ?? $noop ??= new NoopTextMapPropagator();
+    }
+}
diff --git a/tests/Unit/API/Common/Instrumentation/InstrumentationTest.php b/tests/Unit/API/Common/Instrumentation/InstrumentationTest.php
new file mode 100644
index 000000000..b4d192701
--- /dev/null
+++ b/tests/Unit/API/Common/Instrumentation/InstrumentationTest.php
@@ -0,0 +1,91 @@
+<?php
+
+declare(strict_types=1);
+
+namespace OpenTelemetry\Tests\Unit\API\Common\Instrumentation;
+
+use OpenTelemetry\API\Common\Instrumentation\CachedInstrumentation;
+use OpenTelemetry\API\Common\Instrumentation\Configurator;
+use OpenTelemetry\API\Common\Instrumentation\Globals;
+use OpenTelemetry\API\Metrics\MeterInterface;
+use OpenTelemetry\API\Metrics\MeterProviderInterface;
+use OpenTelemetry\API\Metrics\Noop\NoopMeter;
+use OpenTelemetry\API\Metrics\Noop\NoopMeterProvider;
+use OpenTelemetry\API\Trace\NoopTracer;
+use OpenTelemetry\API\Trace\NoopTracerProvider;
+use OpenTelemetry\API\Trace\TracerInterface;
+use OpenTelemetry\API\Trace\TracerProviderInterface;
+use OpenTelemetry\Context\Propagation\NoopTextMapPropagator;
+use OpenTelemetry\Context\Propagation\TextMapPropagatorInterface;
+use PHPUnit\Framework\TestCase;
+
+/**
+ * @covers \OpenTelemetry\API\Common\Instrumentation\Globals
+ * @covers \OpenTelemetry\API\Common\Instrumentation\CachedInstrumentation
+ * @covers \OpenTelemetry\API\Common\Instrumentation\Configurator
+ * @covers \OpenTelemetry\API\Common\Instrumentation\ContextKeys
+ */
+final class InstrumentationTest extends TestCase
+{
+    public function test_globals_not_configured_returns_noop_instances(): void
+    {
+        $this->assertInstanceOf(NoopTracerProvider::class, Globals::tracerProvider());
+        $this->assertInstanceOf(NoopMeterProvider::class, Globals::meterProvider());
+        $this->assertInstanceOf(NoopTextMapPropagator::class, Globals::propagator());
+    }
+
+    public function test_globals_returns_configured_instances(): void
+    {
+        $tracerProvider = $this->createMock(TracerProviderInterface::class);
+        $meterProvider = $this->createMock(MeterProviderInterface::class);
+        $propagator = $this->createMock(TextMapPropagatorInterface::class);
+
+        $scope = Configurator::create()
+            ->withTracerProvider($tracerProvider)
+            ->withMeterProvider($meterProvider)
+            ->withPropagator($propagator)
+            ->activate();
+
+        try {
+            $this->assertSame($tracerProvider, Globals::tracerProvider());
+            $this->assertSame($meterProvider, Globals::meterProvider());
+            $this->assertSame($propagator, Globals::propagator());
+        } finally {
+            $scope->detach();
+        }
+    }
+
+    public function test_instrumentation_not_configured_returns_noop_instances(): void
+    {
+        $instrumentation = new CachedInstrumentation('', null, null, []);
+
+        $this->assertInstanceOf(NoopTracer::class, $instrumentation->tracer());
+        $this->assertInstanceOf(NoopMeter::class, $instrumentation->meter());
+    }
+
+    public function test_instrumentation_returns_configured_instances(): void
+    {
+        $instrumentation = new CachedInstrumentation('', null, null, []);
+
+        $tracer = $this->createMock(TracerInterface::class);
+        $tracerProvider = $this->createMock(TracerProviderInterface::class);
+        $tracerProvider->method('getTracer')->willReturn($tracer);
+        $meter = $this->createMock(MeterInterface::class);
+        $meterProvider = $this->createMock(MeterProviderInterface::class);
+        $meterProvider->method('getMeter')->willReturn($meter);
+        $propagator = $this->createMock(TextMapPropagatorInterface::class);
+
+        $scope = Configurator::create()
+            ->withTracerProvider($tracerProvider)
+            ->withMeterProvider($meterProvider)
+            ->withPropagator($propagator)
+            ->activate();
+
+        try {
+            $this->assertSame($tracer, $instrumentation->tracer());
+            $this->assertSame($meter, $instrumentation->meter());
+        } finally {
+            $scope->detach();
+        }
+    }
+}