libdispatch-187.5.tar.gz

[apple/libdispatch.git] / private / queue_private.h

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+/*
+ * Copyright (c) 2008-2010 Apple Inc. All rights reserved.
+ *
+ * @APPLE_APACHE_LICENSE_HEADER_START@
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ * @APPLE_APACHE_LICENSE_HEADER_END@
+ */
+
+/*
+ * IMPORTANT: This header file describes INTERNAL interfaces to libdispatch
+ * which are subject to change in future releases of Mac OS X. Any applications
+ * relying on these interfaces WILL break.
+ */
+
+#ifndef __DISPATCH_QUEUE_PRIVATE__
+#define __DISPATCH_QUEUE_PRIVATE__
+
+#ifndef __DISPATCH_INDIRECT__
+#error "Please #include <dispatch/dispatch.h> instead of this file directly."
+#include <dispatch/base.h> // for HeaderDoc
+#endif
+
+__BEGIN_DECLS
+
+
+/*!
+ * @enum dispatch_queue_flags_t
+ *
+ * @constant DISPATCH_QUEUE_OVERCOMMIT
+ * The queue will create a new thread for invoking blocks, regardless of how
+ * busy the computer is.
+ */
+enum {
+       DISPATCH_QUEUE_OVERCOMMIT = 0x2ull,
+};
+
+#define DISPATCH_QUEUE_FLAGS_MASK (DISPATCH_QUEUE_OVERCOMMIT)
+
+/*!
+ * @function dispatch_queue_set_width
+ *
+ * @abstract
+ * Set the width of concurrency for a given queue. The width of a serial queue
+ * is one.
+ *
+ * @discussion
+ * This SPI is DEPRECATED and will be removed in a future release.
+ * Uses of this SPI to make a queue concurrent by setting its width to LONG_MAX
+ * should be replaced by passing DISPATCH_QUEUE_CONCURRENT to
+ * dispatch_queue_create().
+ * Uses of this SPI to limit queue concurrency are not recommended and should
+ * be replaced by alternative mechanisms such as a dispatch semaphore created
+ * with the desired concurrency width.
+ *
+ * @param queue
+ * The queue to adjust. Passing the main queue or a global concurrent queue
+ * will be ignored.
+ *
+ * @param width
+ * The new maximum width of concurrency depending on available resources.
+ * If zero is passed, then the value is promoted to one.
+ * Negative values are magic values that map to automatic width values.
+ * Unknown negative values default to DISPATCH_QUEUE_WIDTH_MAX_LOGICAL_CPUS.
+ */
+#define DISPATCH_QUEUE_WIDTH_ACTIVE_CPUS               -1
+#define DISPATCH_QUEUE_WIDTH_MAX_PHYSICAL_CPUS -2
+#define DISPATCH_QUEUE_WIDTH_MAX_LOGICAL_CPUS  -3
+
+__OSX_AVAILABLE_STARTING(__MAC_10_6,__IPHONE_4_0)
+DISPATCH_EXPORT DISPATCH_NONNULL_ALL DISPATCH_NOTHROW
+void
+dispatch_queue_set_width(dispatch_queue_t dq, long width); // DEPRECATED
+
+/*!
+ * @function dispatch_set_current_target_queue
+ *
+ * @abstract
+ * Synchronously sets the target queue of the current serial queue.
+ *
+ * @discussion
+ * This SPI is provided for a limited purpose case when calling
+ * dispatch_set_target_queue() is not sufficient. It works similarly to
+ * dispatch_set_target_queue() except the target queue of the current queue
+ * is immediately changed so that pending blocks on the queue will run on the
+ * new target queue. Calling this from outside of a block executing on a serial
+ * queue is undefined.
+ *
+ * @param queue
+ * The new target queue for the object. The queue is retained, and the
+ * previous target queue, if any, is released.
+ * If queue is DISPATCH_TARGET_QUEUE_DEFAULT, set the object's target queue
+ * to the default target queue for the given object type.
+ */
+
+__OSX_AVAILABLE_STARTING(__MAC_10_7,__IPHONE_5_0)
+DISPATCH_EXPORT DISPATCH_NOTHROW
+void
+dispatch_set_current_target_queue(dispatch_queue_t queue);
+
+__OSX_AVAILABLE_STARTING(__MAC_10_6,__IPHONE_4_0)
+DISPATCH_EXPORT const struct dispatch_queue_offsets_s {
+       // always add new fields at the end
+       const uint16_t dqo_version;
+       const uint16_t dqo_label;
+       const uint16_t dqo_label_size;
+       const uint16_t dqo_flags;
+       const uint16_t dqo_flags_size;
+       const uint16_t dqo_serialnum;
+       const uint16_t dqo_serialnum_size;
+       const uint16_t dqo_width;
+       const uint16_t dqo_width_size;
+       const uint16_t dqo_running;
+       const uint16_t dqo_running_size;
+} dispatch_queue_offsets;
+
+
+__END_DECLS
+
+#endif