Refactor Context (#746)

Author: tidal

Context.php

@@ -9,55 +9,35 @@
  */
 final class Context
 {
-
     /**
      * @var ContextStorageInterface&ExecutionContextAwareInterface
      */
     private static ContextStorageInterface $storage;
-
-    private static ?Context $root = null;
-
-    /**
-     * @internal
-     *
-     * @param ContextStorageInterface&ExecutionContextAwareInterface $storage
-     */
-    public static function setStorage(ContextStorageInterface $storage): void
-    {
-        self::$storage = $storage;
-    }
-
+    private static ?self $root = null;
+    private ?ContextKey $key;
     /**
-     * @return ContextStorageInterface&ExecutionContextAwareInterface
+     * @var mixed
      */
-    public static function storage(): ContextStorageInterface
-    {
-        /** @psalm-suppress RedundantPropertyInitializationCheck */
-        return self::$storage ??= new ContextStorage();
-    }
+    private $value;
+    private ?self $parent;
 
     /**
-     * @param non-empty-string $key
+     * This is a general purpose read-only key-value store. Read-only in the sense that adding a new value does not
+     * mutate the existing context, but returns a new Context which has the new value added.
      *
-     * @see https://github.com/open-telemetry/opentelemetry-specification/blob/v1.6.1/specification/context/context.md#create-a-key
+     * In practical terms, this is implemented as a linked list of Context instances, with each one holding a reference
+     * to the key object, the value that corresponds to the key, and an optional reference to the parent Context
+     * (i.e. the next link in the linked list chain)
+     *
+     * @param ContextKey|null $key The key object. Should only be null when creating an "empty" context
+     * @param mixed $value
+     * @param Context|null $parent Reference to the parent object
      */
-    public static function createKey(string $key): ContextKey
-    {
-        return new ContextKey($key);
-    }
-
-    public static function getCurrent(): Context
-    {
-        return self::storage()->current();
-    }
-
-    public static function getRoot(): self
+    private function __construct(?ContextKey $key=null, $value=null, ?self $parent=null)
     {
-        if (null === self::$root) {
-            self::$root = new self();
-        }
-
-        return self::$root;
+        $this->key = $key;
+        $this->value = $value;
+        $this->parent = $parent;
     }
 
     /**
@@ -66,69 +46,41 @@ public static function getRoot(): self
      * This will operate on the "current" global context in that scenario.
      *
      * There are two ways to call this function:
-     * 1) With a $ctx value:
-     *    Context::getValue($key, $ctx) is functionally equivalent to $ctx->get($key)
-     * 2) Without a $ctx value:
+     * 1) With a $context value:
+     *    Context::getValue($key, $context) is functionally equivalent to $context->get($key)
+     * 2) Without a $context value:
      *    This will fetch the "current" Context if one exists or create one if not, then attempt to get the value from it.
      *
      * @param ContextKey $key
-     * @param Context|null $ctx
+     * @param Context|null $context
      *
      * @return mixed
      */
-    public static function getValue(ContextKey $key, ?Context $ctx=null)
+    public static function getValue(ContextKey $key, ?self $context=null)
     {
-        $ctx ??= self::getCurrent();
+        $context ??= self::getCurrent();
 
-        return $ctx->get($key);
+        return $context->get($key);
     }
 
-    private ?ContextKey $key;
-
-    /**
-     * @var mixed
-     */
-    private $value;
-
-    private ?Context $parent;
-
     /**
-     * This is a general purpose read-only key-value store. Read-only in the sense that adding a new value does not
-     * mutate the existing context, but returns a new Context which has the new value added.
-     *
-     * In practical terms, this is implemented as a linked list of Context instances, with each one holding a reference
-     * to the key object, the value that corresponds to the key, and an optional reference to the parent Context
-     * (i.e. the next link in the linked list chain)
-     *
-     * @param ContextKey|null $key The key object. Should only be null when creating an "empty" context
-     * @param mixed $value
-     * @param Context|null $parent Reference to the parent object
-     */
-    private function __construct(?ContextKey $key=null, $value=null, ?Context $parent=null)
-    {
-        $this->key = $key;
-        $this->value = $value;
-        $this->parent = $parent;
-    }
-
-    /**
-     * This adds a k/v pair to this Context. We do this by instantiating a new Context instance with the k/v and pass
+     * This adds a key/value pair to this Context. We do this by instantiating a new Context instance with the key/value and pass
      * a reference to $this as the "parent" creating the linked list chain.
      *
      * @param ContextKey $key
      * @param mixed $value
      *
-     * @return Context a new Context containing the k/v
+     * @return Context a new Context containing the key/value
      */
-    public function with(ContextKey $key, $value): Context
+    public function with(ContextKey $key, $value): self
     {
         return new self($key, $value, $this);
     }
 
     /**
      * @todo: Implement this on the API side
      */
-    public function withContextValue(ImplicitContextKeyedInterface $value): Context
+    public function withContextValue(ImplicitContextKeyedInterface $value): self
     {
         return $value->storeInContext($this);
     }
@@ -158,4 +110,43 @@ public function get(ContextKey $key)
 
         return null;
     }
+
+    /**
+     * @internal
+     *
+     * @param ContextStorageInterface&ExecutionContextAwareInterface $storage
+     */
+    public static function setStorage(ContextStorageInterface $storage): void
+    {
+        self::$storage = $storage;
+    }
+
+    /**
+     * @return ContextStorageInterface&ExecutionContextAwareInterface
+     */
+    public static function storage(): ContextStorageInterface
+    {
+        /** @psalm-suppress RedundantPropertyInitializationCheck */
+        return self::$storage ??= new ContextStorage();
+    }
+
+    /**
+     * @param non-empty-string $key
+     *
+     * @see https://github.com/open-telemetry/opentelemetry-specification/blob/v1.6.1/specification/context/context.md#create-a-key
+     */
+    public static function createKey(string $key): ContextKey
+    {
+        return new ContextKey($key);
+    }
+
+    public static function getCurrent(): self
+    {
+        return self::storage()->current();
+    }
+
+    public static function getRoot(): self
+    {
+        return self::$root ??= new self();
+    }
 }