Serialize exception trace arguments in child processes and threads

composer.json

@@ -38,6 +38,8 @@
             "Amp\\Parallel\\": "lib"
         },
         "files": [
+            "lib/Context/functions.php",
+            "lib/Sync/functions.php",
             "lib/Worker/functions.php"
         ]
     },

lib/Context/functions.php

@@ -0,0 +1,33 @@
+<?php
+
+namespace Amp\Parallel\Context;
+
+use Amp\Promise;
+
+/**
+ * @param string|string[] $script
+ *
+ * @return Context
+ */
+function create($script): Context
+{
+    if (Parallel::isSupported()) {
+        return new Parallel($script);
+    }
+
+    return new Process($script);
+}
+
+/**
+ * @param string|string[] $script
+ *
+ * @return Promise<Context>
+ */
+function run($script): Promise
+{
+    if (Parallel::isSupported()) {
+        return Parallel::run($script);
+    }
+
+    return Process::run($script);
+}

lib/Sync/ExitFailure.php

@@ -13,7 +13,7 @@ final class ExitFailure implements ExitResult
     /** @var int|string */
     private $code;
 
-    /** @var array */
+    /** @var string[] */
     private $trace;
 
     /** @var self|null */
@@ -24,7 +24,7 @@ final class ExitFailure implements ExitResult
         $this->type = \get_class($exception);
         $this->message = $exception->getMessage();
         $this->code = $exception->getCode();
-        $this->trace = $exception->getTraceAsString();
+        $this->trace = flattenThrowableBacktrace($exception);
 
         if ($previous = $exception->getPrevious()) {
             $this->previous = new self($previous);
@@ -53,7 +53,7 @@ final class ExitFailure implements ExitResult
                 $this->code,
                 PanicError::class
             ),
-            $this->trace,
+            \implode("\n", $this->trace),
             $previous
         );
     }

lib/Sync/functions.php

@@ -0,0 +1,75 @@
+<?php
+
+namespace Amp\Parallel\Sync;
+
+/**
+ * @param \Throwable $exception
+ *
+ * @return string[] Serializable array of strings representing the exception backtrace including function arguments.
+ */
+function flattenThrowableBacktrace(\Throwable $exception): array
+{
+    $output = [];
+    $counter = 0;
+    $trace = $exception->getTrace();
+
+    foreach ($trace as $call) {
+        if (isset($call['class'])) {
+            $name = $call['class'] . $call['type'] . $call['function'];
+        } else {
+            $name = $call['function'];
+        }
+
+        $args = \implode(', ', \array_map(__NAMESPACE__ . '\\flattenArgument', $call['args']));
+
+        $output[] = \sprintf(
+            '#%d %s(%d): %s(%s)',
+            $counter++,
+            $call['file'] ?? '[internal function]',
+            $call['line'] ?? 0,
+            $name,
+            $args
+        );
+    }
+
+    return $output;
+}
+
+/**
+ * @param mixed $value
+ *
+ * @return string Serializable string representation of $value for backtraces.
+ */
+function flattenArgument($value): string
+{
+    if ($value instanceof \Closure) {
+        $closureReflection = new \ReflectionFunction($value);
+        return \sprintf(
+            'Closure(%s:%s)',
+            $closureReflection->getFileName(),
+            $closureReflection->getStartLine()
+        );
+    }
+
+    if (\is_object($value)) {
+        return \sprintf('Object(%s)', \get_class($value));
+    }
+
+    if (\is_array($value)) {
+        return 'Array([' . \implode(', ', \array_map(__FUNCTION__, $value)) . '])';
+    }
+
+    if (\is_resource($value)) {
+        return \sprintf('Resource(%s)', \get_resource_type($value));
+    }
+
+    if (\is_string($value)) {
+        return '"' . $value . '"';
+    }
+
+    if (\is_null($value)) {
+        return 'null';
+    }
+
+    return (string) $value;
+}

lib/Worker/Internal/TaskFailure.php

@@ -3,6 +3,7 @@
 namespace Amp\Parallel\Worker\Internal;
 
 use Amp\Failure;
+use Amp\Parallel\Sync;
 use Amp\Parallel\Worker\TaskError;
 use Amp\Parallel\Worker\TaskException;
 use Amp\Promise;
@@ -25,7 +26,7 @@ final class TaskFailure extends TaskResult
     /** @var int|string */
     private $code;
 
-    /** @var array */
+    /** @var string[] */
     private $trace;
 
     /** @var self|null */
@@ -38,7 +39,7 @@ final class TaskFailure extends TaskResult
         $this->parent = $exception instanceof \Error ? self::PARENT_ERROR : self::PARENT_EXCEPTION;
         $this->message = $exception->getMessage();
         $this->code = $exception->getCode();
-        $this->trace = $exception->getTraceAsString();
+        $this->trace = Sync\flattenThrowableBacktrace($exception);
 
         if ($previous = $exception->getPrevious()) {
             $this->previous = new self($id, $previous);
@@ -61,7 +62,7 @@ final class TaskFailure extends TaskResult
             return new TaskError(
                 $this->type,
                 \sprintf($format, $this->type, $this->message, $this->code, TaskError::class),
-                $this->trace,
+                \implode("\n", $this->trace),
                 $previous
             );
         }
@@ -69,7 +70,7 @@ final class TaskFailure extends TaskResult
         return new TaskException(
             $this->type,
             \sprintf($format, $this->type, $this->message, $this->code, TaskException::class),
-            $this->trace,
+            \implode("\n", $this->trace),
             $previous
         );
     }