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diff --git a/libparc/parc/concurrent/parc_Synchronizer.h b/libparc/parc/concurrent/parc_Synchronizer.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_Synchronizer.h
+ * @ingroup threading
+ * @brief A simple mutual exclusive synchronization implementation.
+ *
+ * Detailed Description
+ *
+ */
+#ifndef PARCLibrary_parc_Barrier
+#define PARCLibrary_parc_Barrier
+#include <stdbool.h>
+
+#include <parc/algol/parc_JSON.h>
+
+struct PARCSynchronizer;
+typedef struct PARCSynchronizer PARCSynchronizer;
+
+/**
+ * Increase the number of references to a `PARCSynchronizer` instance.
+ *
+ * Note that new `PARCSynchronizer` is not created,
+ * only that the given `PARCSynchronizer` reference count is incremented.
+ * Discard the reference by invoking `parcSynchronizer_Release`.
+ *
+ * @param [in] instance A pointer to a valid PARCSynchronizer instance.
+ *
+ * @return The same value as @p instance.
+ *
+ * Example:
+ * @code
+ * {
+ *     PARCSynchronizer *a = parcSynchronizer_Create();
+ *
+ *     PARCSynchronizer *b = parcSynchronizer_Acquire();
+ *
+ *     parcSynchronizer_Release(&a);
+ *     parcSynchronizer_Release(&b);
+ * }
+ * @endcode
+ */
+PARCSynchronizer *parcSynchronizer_Acquire(const PARCSynchronizer *instance);
+
+#ifdef PARCLibrary_DISABLE_VALIDATION
+#  define parcSynchronizer_OptionalAssertValid(_instance_)
+#else
+#  define parcSynchronizer_OptionalAssertValid(_instance_) parcSynchronizer_AssertValid(_instance_)
+#endif
+
+/**
+ * Assert that the given `PARCSynchronizer` instance is valid.
+ *
+ * @param [in] instance A pointer to a valid PARCSynchronizer instance.
+ *
+ * Example:
+ * @code
+ * {
+ *     PARCSynchronizer *a = parcSynchronizer_Create();
+ *
+ *     parcSynchronizer_AssertValid(a);
+ *
+ *     printf("Instance is valid.\n");
+ *
+ *     parcSynchronizer_Release(&b);
+ * }
+ * @endcode
+ */
+void parcSynchronizer_AssertValid(const PARCSynchronizer *instance);
+
+/**
+ * Create an instance of PARCSynchronizer
+ *
+ * <#Paragraphs Of Explanation#>
+ *
+ * @return non-NULL A pointer to a valid PARCSynchronizer instance.
+ * @return NULL An error occurred.
+ *
+ * Example:
+ * @code
+ * {
+ *     PARCSynchronizer *a = parcSynchronizer_Create();
+ *
+ *     parcSynchronizer_Release(&a);
+ * }
+ * @endcode
+ */
+PARCSynchronizer *parcSynchronizer_Create(void);
+
+/**
+ * Print a human readable representation of the given `PARCSynchronizer`.
+ *
+ * @param [in] instance A pointer to a valid PARCSynchronizer instance.
+ * @param [in] indentation The indentation level to use for printing.
+ *
+ * Example:
+ * @code
+ * {
+ *     PARCSynchronizer *a = parcSynchronizer_Create();
+ *
+ *     parcSynchronizer_Display(a, 0);
+ *
+ *     parcSynchronizer_Release(&a);
+ * }
+ * @endcode
+ */
+void parcSynchronizer_Display(const PARCSynchronizer *instance, int indentation);
+
+/**
+ * Returns a hash code value for the given instance.
+ *
+ * The general contract of `HashCode` is:
+ *
+ * Whenever it is invoked on the same instance more than once during an execution of an application,
+ * the `HashCode` function must consistently return the same value,
+ * provided no information used in a corresponding comparisons on the instance is modified.
+ *
+ * This value need not remain consistent from one execution of an application to another execution of the same application.
+ * If two instances are equal according to the {@link parcSynchronizer_Equals} method,
+ * then calling the {@link parcSynchronizer_HashCode} method on each of the two instances must produce the same integer result.
+ *
+ * It is not required that if two instances are unequal according to the
+ * {@link parcSynchronizer_Equals} function,
+ * then calling the `parcSynchronizer_HashCode`
+ * method on each of the two objects must produce distinct integer results.
+ *
+ * @param [in] instance A pointer to a valid PARCSynchronizer instance.
+ *
+ * @return The hashcode for the given instance.
+ *
+ * Example:
+ * @code
+ * {
+ *     PARCSynchronizer *a = parcSynchronizer_Create();
+ *
+ *     uint32_t hashValue = parcSynchronizer_HashCode(buffer);
+ *     parcSynchronizer_Release(&a);
+ * }
+ * @endcode
+ */
+int parcSynchronizer_HashCode(const PARCSynchronizer *instance);
+
+/**
+ * Determine if an instance of `PARCSynchronizer` 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 PARCSynchronizer instance.
+ *
+ * @return true The instance is valid.
+ * @return false The instance is not valid.
+ *
+ * Example:
+ * @code
+ * {
+ *     PARCSynchronizer *a = parcSynchronizer_Create();
+ *
+ *     if (parcSynchronizer_IsValid(a)) {
+ *         printf("Instance is valid.\n");
+ *     }
+ *
+ *     parcSynchronizer_Release(&a);
+ * }
+ * @endcode
+ *
+ */
+bool parcSynchronizer_IsValid(const PARCSynchronizer *instance);
+
+/**
+ * Release a previously acquired reference to the given `PARCSynchronizer` 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
+ * {
+ *     PARCSynchronizer *a = parcSynchronizer_Create();
+ *
+ *     parcSynchronizer_Release(&a);
+ * }
+ * @endcode
+ */
+void parcSynchronizer_Release(PARCSynchronizer **instancePtr);
+
+/**
+ * Attempt to lock the given PARCSynchronizer.
+ *
+ * If the synchronizer is already locked, this function returns `false`.
+ * Otherwise, the lock is established and this function returns `true`.
+ *
+ * @param [in] barrier A pointer to a valid PARCSynchronizer instance.
+ *
+ * @return `true` The PARCSynchronizer was successfully set.
+ * @return `false` The PARCSynchronizer could not be set.
+ *
+ * Example:
+ * @code
+ * {
+ *     <#example#>
+ * }
+ * @endcode
+ */
+bool parcSynchronizer_TryLock(PARCSynchronizer *barrier);
+
+/**
+ * Lock the given PARCSynchronizer.
+ *
+ * If the synchronizer is already locked, this function blocks the caller until it is able to acquire the lock.
+ *
+ * @param [in] barrier A pointer to a valid PARCSynchronizer instance.
+ *
+ * Example:
+ * @code
+ * {
+ *     <#example#>
+ * }
+ * @endcode
+ */
+void parcSynchronizer_Lock(PARCSynchronizer *barrier);
+
+/**
+ * Unlock the given PARCSynchronizer.
+ *
+ * @param [in] barrier A pointer to a valid PARCSynchronizer instance.
+ *
+ * Example:
+ * @code
+ * {
+ *     <#example#>
+ * }
+ * @endcode
+ */
+void parcSynchronizer_Unlock(PARCSynchronizer *barrier);
+
+/**
+ * Check if a PARCSynchronizer is locked.
+ *
+ * @param [in] synchronizer A pointer to a valid PARCSynchronizer instance.
+ *
+ * @return true The specified synchronizer is currently locked.
+ *
+ * Example:
+ * @code
+ * {
+ *     PARCSynchronizer *a = parcSynchronizer_Create();
+ *
+ *     if (parcSynchronizer_IsLocked(a) == true) {
+ *         printf("A PARCSynchronizer cannot be created in the locked state.\n");
+ *     }
+ *
+ *     parcSynchronizer_Release(&a);
+ * }
+ * @endcode
+ */
+bool parcSynchronizer_IsLocked(const PARCSynchronizer *synchronizer);
+#endif