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diff --git a/libparc/parc/concurrent/parc_Lock.h b/libparc/parc/concurrent/parc_Lock.h
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+/*
+ * Copyright (c) 2017 Cisco and/or its affiliates.
+ * 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.
+ */
+
+/**
+ * @file parc_Lock.h
+ * @ingroup threading
+ * @brief <#Brief Description#>
+ *
+ * <#Detailed Description#>
+ *
+ */
+#ifndef PARCLibrary_parc_Lock
+#define PARCLibrary_parc_Lock
+#include <stdbool.h>
+
+#include <parc/algol/parc_HashCode.h>
+#include <parc/algol/parc_JSON.h>
+
+struct PARCLock;
+typedef struct PARCLock PARCLock;
+
+/**
+ * Increase the number of references to a `PARCLock` instance.
+ *
+ * Note that new `PARCLock` is not created,
+ * only that the given `PARCLock` reference count is incremented.
+ * Discard the reference by invoking `parcLock_Release`.
+ *
+ * @param [in] instance A pointer to a valid PARCLock instance.
+ *
+ * @return The same value as @p instance.
+ *
+ * Example:
+ * @code
+ * {
+ *     PARCLock *a = parcLock_Create();
+ *
+ *     PARCLock *b = parcLock_Acquire();
+ *
+ *     parcLock_Release(&a);
+ *     parcLock_Release(&b);
+ * }
+ * @endcode
+ */
+PARCLock *parcLock_Acquire(const PARCLock *instance);
+
+#ifdef PARCLibrary_DISABLE_VALIDATION
+#  define parcLock_OptionalAssertValid(_instance_)
+#else
+#  define parcLock_OptionalAssertValid(_instance_) parcLock_AssertValid(_instance_)
+#endif
+
+/**
+ * Assert that the given `PARCLock` instance is valid.
+ *
+ * @param [in] instance A pointer to a valid PARCLock instance.
+ *
+ * Example:
+ * @code
+ * {
+ *     PARCLock *a = parcLock_Create();
+ *
+ *     parcLock_AssertValid(a);
+ *
+ *     printf("Instance is valid.\n");
+ *
+ *     parcLock_Release(&b);
+ * }
+ * @endcode
+ */
+void parcLock_AssertValid(const PARCLock *instance);
+
+/**
+ * Create an instance of PARCLock
+ *
+ * <#Paragraphs Of Explanation#>
+ *
+ * @return non-NULL A pointer to a valid PARCLock instance.
+ * @return NULL An error occurred.
+ *
+ * Example:
+ * @code
+ * {
+ *     PARCLock *a = parcLock_Create();
+ *
+ *     parcLock_Release(&a);
+ * }
+ * @endcode
+ */
+PARCLock *parcLock_Create(void);
+
+/**
+ * Compares @p instance with @p other for order.
+ *
+ * Returns a negative integer, zero, or a positive integer as @p instance
+ * is less than, equal to, or greater than @p other.
+ *
+ * @param [in] instance A pointer to a valid PARCLock instance.
+ * @param [in] other A pointer to a valid PARCLock instance.
+ *
+ * @return <0 Instance is less than @p other.
+ * @return 0 Instance a and instance b compare the same.
+ * @return >0 Instance a is greater than instance b.
+ *
+ * Example:
+ * @code
+ * {
+ *     PARCLock *a = parcLock_Create();
+ *     PARCLock *b = parcLock_Create();
+ *
+ *     if (parcLock_Compare(a, b) == 0) {
+ *         printf("Instances are equal.\n");
+ *     }
+ *
+ *     parcLock_Release(&a);
+ *     parcLock_Release(&b);
+ * }
+ * @endcode
+ *
+ * @see parcLock_Equals
+ */
+int parcLock_Compare(const PARCLock *instance, const PARCLock *other);
+
+/**
+ * Print a human readable representation of the given `PARCLock`.
+ *
+ * @param [in] instance A pointer to a valid PARCLock instance.
+ * @param [in] indentation The indentation level to use for printing.
+ *
+ * Example:
+ * @code
+ * {
+ *     PARCLock *a = parcLock_Create();
+ *
+ *     parcLock_Display(a, 0);
+ *
+ *     parcLock_Release(&a);
+ * }
+ * @endcode
+ */
+void parcLock_Display(const PARCLock *instance, int indentation);
+
+/**
+ * Determine if an instance of `PARCLock` is valid.
+ *
+ * Valid means the internal state of the type is consistent with its required current or future behaviour.
+ * This may include the validation of internal instances of types.
+ *
+ * @param [in] instance A pointer to a valid PARCLock instance.
+ *
+ * @return true The instance is valid.
+ * @return false The instance is not valid.
+ *
+ * Example:
+ * @code
+ * {
+ *     PARCLock *a = parcLock_Create();
+ *
+ *     if (parcLock_IsValid(a)) {
+ *         printf("Instance is valid.\n");
+ *     }
+ *
+ *     parcLock_Release(&a);
+ * }
+ * @endcode
+ *
+ */
+bool parcLock_IsValid(const PARCLock *instance);
+
+/**
+ * Release a previously acquired reference to the given `PARCLock` instance,
+ * decrementing the reference count for the instance.
+ *
+ * The pointer to the instance is set to NULL as a side-effect of this function.
+ *
+ * If the invocation causes the last reference to the instance to be released,
+ * the instance is deallocated and the instance's implementation will perform
+ * additional cleanup and release other privately held references.
+ *
+ * @param [in,out] instancePtr A pointer to a pointer to the instance to release.
+ *
+ * Example:
+ * @code
+ * {
+ *     PARCLock *a = parcLock_Create();
+ *
+ *     parcLock_Release(&a);
+ * }
+ * @endcode
+ */
+void parcLock_Release(PARCLock **instancePtr);
+
+/**
+ * Append a representation of the specified `PARCLock` instance to the given `PARCBufferComposer`.
+ *
+ * @param [in] name A pointer to a `PARCLock` instance whose representation should be appended to the @p composer.
+ * @param [in,out] composer A pointer to a `PARCBufferComposer` instance to be modified.
+ *
+ * @return NULL Cannot allocate memory.
+ * @return non-NULL The @p composer.
+ *
+ * Example:
+ * @code
+ * {
+ *     PARCBufferComposer *result = parcBufferComposer_Create();
+ *
+ *     parcLock_BuildString(instance, result);
+ *
+ *     char *string = parcBufferComposer_ToString(result);
+ *     printf("Hello: %s\n", string);
+ *     parcMemory_Deallocate(string);
+ *
+ *     parcBufferComposer_Release(&result);
+ * }
+ * @endcode
+ */
+PARCBufferComposer *parcLock_BuildString(const PARCLock *name, PARCBufferComposer *composer);
+
+/**
+ * Produce a null-terminated string representation of the specified `PARCLock`.
+ *
+ * The result must be freed by the caller via {@link parcMemory_Deallocate}.
+ *
+ * @param [in] instance A pointer to a valid PARCLock instance.
+ *
+ * @return NULL Cannot allocate memory.
+ * @return non-NULL A pointer to an allocated, null-terminated C string that must be deallocated via {@link parcMemory_Deallocate}.
+ *
+ * Example:
+ * @code
+ * {
+ *     PARCLock *a = parcLock_Create();
+ *
+ *     char *string = parcLock_ToString(a);
+ *
+ *     parcLock_Release(&a);
+ *
+ *     parcMemory_Deallocate(&string);
+ * }
+ * @endcode
+ *
+ * @see parcLock_Display
+ */
+char *parcLock_ToString(const PARCLock *instance);
+
+/**
+ * Obtain the lock on the given `PARCLock` instance.
+ *
+ * If the lock is already held by another thread, this function will block.
+ * If the lock is aleady held by the current thread, this function will return `false`.
+ *
+ * Implementors must avoid deadlock by attempting to lock the object a second time within the same calling thread.
+ *
+ * @param [in] lock A pointer to a valid `PARCLock` instance.
+ *
+ * @return true The lock was obtained successfully.
+ * @return false The lock is already held by the current thread, or the `PARCLock` is invalid.
+ *
+ * Example:
+ * @code
+ * {
+ *     if (parcLock_Lock(lock)) {
+ *
+ *     }
+ * }
+ * @endcode
+ */
+bool parcLock_Lock(PARCLock *lock);
+
+/**
+ * Try to obtain the advisory lock on the given `PARCObject` instance.
+ *
+ * Once the lock is obtained, the caller must release the lock via `parcObject_Unlock`.
+ *
+ * @param [in] lock A pointer to a valid `PARCObject` instance.
+ *
+ * @return true The `PARCObject` is locked.
+ * @return false The `PARCObject` is unlocked.
+ *
+ * Example:
+ * @code
+ * {
+ *     while (parcLock_TryLock(object))
+ *         ;
+ * }
+ * @endcode
+ */
+bool parcLock_TryLock(PARCLock *lock);
+
+/**
+ * Try to unlock the advisory lock on the given PARCObject instance.
+ *
+ * @param [in] lock A pointer to a valid PARCObject instance.
+ *
+ * @return true The PARCObject was locked and now is unlocked.
+ * @return false The PARCObject was not locked and remains unlocked.
+ *
+ * Example:
+ * @code
+ * {
+ *     parcLock_Unlock(object);
+ * }
+ * @endcode
+ */
+bool parcLock_Unlock(PARCLock *lock);
+
+/**
+ * Determine if the advisory lock on the given PARCObject instance is locked.
+ *
+ * @param [in] lock A pointer to a valid PARCObject instance.
+ *
+ * @return true The PARCObject is locked.
+ * @return false The PARCObject is unlocked.
+ * Example:
+ * @code
+ * {
+ *     <#example#>
+ * }
+ * @endcode
+ */
+bool parcLock_IsLocked(const PARCLock *lock);
+
+/**
+ * Causes the calling thread to wait until either another thread invokes the parcObject_Notify() function on the same object.
+ *
+ * The calling thread must own this object's lock.
+ * The calling thread will release ownership of this lock and wait until another thread invokes `parcObject_Notify`
+ * on the same object. The original calling thread then re-obtains ownership of the lock and resumes execution.
+ *
+ * This function must only be called by a thread that is the owner of this object's lock.
+ *
+ * @param [in] lock A pointer to a valid PARCObject instance.
+ *
+ * Example:
+ * @code
+ * {
+ *
+ *     parcObject_Wait(object);
+ * }
+ * @endcode
+ */
+void parcLock_Wait(PARCLock *lock);
+
+/**
+ * Wakes up a single thread that is waiting on this object (see `parcObject_Wait)`.
+ * If any threads are waiting on this object, one of them is chosen to be awakened.
+ * The choice is arbitrary and occurs at the discretion of the underlying implementation.
+ *
+ * The awakened thread will not be able to proceed until the current thread relinquishes the lock on this object.
+ * The awakened thread will compete in the usual manner with any other threads that might be actively
+ * competing to synchronize on this object;
+ * for example, the awakened thread enjoys no reliable privilege or disadvantage in being the next thread to lock this object.
+ *
+ * @param [in] lock A pointer to a valid `PARCObject` instance.
+ *
+ * Example:
+ * @code
+ * {
+ *
+ *     parcObject_Notify(object);
+ * }
+ * @endcode
+ */
+void parcLock_Notify(PARCLock *lock);
+#endif