scripts/thread_safety_generator.py

#!/usr/bin/python3 -i
#
# Copyright (c) 2015-2019 The Khronos Group Inc.
# Copyright (c) 2015-2019 Valve Corporation
# Copyright (c) 2015-2019 LunarG, Inc.
# Copyright (c) 2015-2019 Google Inc.
#
# 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.
#
# Author: Mike Stroyan <stroyan@google.com>
# Author: Mark Lobodzinski <mark@lunarg.com>

import os,re,sys
from generator import *
from common_codegen import *

# ThreadGeneratorOptions - subclass of GeneratorOptions.
#
# Adds options used by ThreadOutputGenerator objects during threading
# layer generation.
#
# Additional members
#   prefixText - list of strings to prefix generated header with
#     (usually a copyright statement + calling convention macros).
#   protectFile - True if multiple inclusion protection should be
#     generated (based on the filename) around the entire header.
#   protectFeature - True if #ifndef..#endif protection should be
#     generated around a feature interface in the header file.
#   genFuncPointers - True if function pointer typedefs should be
#     generated
#   protectProto - If conditional protection should be generated
#     around prototype declarations, set to either '#ifdef'
#     to require opt-in (#ifdef protectProtoStr) or '#ifndef'
#     to require opt-out (#ifndef protectProtoStr). Otherwise
#     set to None.
#   protectProtoStr - #ifdef/#ifndef symbol to use around prototype
#     declarations, if protectProto is set
#   apicall - string to use for the function declaration prefix,
#     such as APICALL on Windows.
#   apientry - string to use for the calling convention macro,
#     in typedefs, such as APIENTRY.
#   apientryp - string to use for the calling convention macro
#     in function pointer typedefs, such as APIENTRYP.
#   indentFuncProto - True if prototype declarations should put each
#     parameter on a separate line
#   indentFuncPointer - True if typedefed function pointers should put each
#     parameter on a separate line
#   alignFuncParam - if nonzero and parameters are being put on a
#     separate line, align parameter names at the specified column
class ThreadGeneratorOptions(GeneratorOptions):
    def __init__(self,
                 conventions = None,
                 filename = None,
                 directory = '.',
                 apiname = None,
                 profile = None,
                 versions = '.*',
                 emitversions = '.*',
                 defaultExtensions = None,
                 addExtensions = None,
                 removeExtensions = None,
                 emitExtensions = None,
                 sortProcedure = regSortFeatures,
                 prefixText = "",
                 genFuncPointers = True,
                 protectFile = True,
                 protectFeature = True,
                 apicall = '',
                 apientry = '',
                 apientryp = '',
                 indentFuncProto = True,
                 indentFuncPointer = False,
                 alignFuncParam = 0,
                 expandEnumerants = True):
        GeneratorOptions.__init__(self, conventions, filename, directory, apiname, profile,
                                  versions, emitversions, defaultExtensions,
                                  addExtensions, removeExtensions, emitExtensions, sortProcedure)
        self.prefixText      = prefixText
        self.genFuncPointers = genFuncPointers
        self.protectFile     = protectFile
        self.protectFeature  = protectFeature
        self.apicall         = apicall
        self.apientry        = apientry
        self.apientryp       = apientryp
        self.indentFuncProto = indentFuncProto
        self.indentFuncPointer = indentFuncPointer
        self.alignFuncParam  = alignFuncParam
        self.expandEnumerants = expandEnumerants


# ThreadOutputGenerator - subclass of OutputGenerator.
# Generates Thread checking framework
#
# ---- methods ----
# ThreadOutputGenerator(errFile, warnFile, diagFile) - args as for
#   OutputGenerator. Defines additional internal state.
# ---- methods overriding base class ----
# beginFile(genOpts)
# endFile()
# beginFeature(interface, emit)
# endFeature()
# genType(typeinfo,name)
# genStruct(typeinfo,name)
# genGroup(groupinfo,name)
# genEnum(enuminfo, name)
# genCmd(cmdinfo)
class ThreadOutputGenerator(OutputGenerator):
    """Generate specified API interfaces in a specific style, such as a C header"""

    inline_copyright_message = """
// This file is ***GENERATED***.  Do Not Edit.
// See layer_chassis_dispatch_generator.py for modifications.

/* Copyright (c) 2015-2019 The Khronos Group Inc.
 * Copyright (c) 2015-2019 Valve Corporation
 * Copyright (c) 2015-2019 LunarG, Inc.
 * Copyright (c) 2015-2019 Google Inc.
 *
 * 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.
 *
 * Author: Mark Lobodzinski <mark@lunarg.com>
 */"""

 # Note that the inline_custom_header_preamble template below contains three embedded template expansion identifiers.
 # These get replaced with generated code sections, and are labeled:
 #  o COUNTER_CLASS_DEFINITIONS_TEMPLATE
 #  o COUNTER_CLASS_INSTANCES_TEMPLATE
 #  o COUNTER_CLASS_BODIES_TEMPLATE
    inline_custom_header_preamble = """
#pragma once

#include <condition_variable>
#include <mutex>
#include <vector>
#include <unordered_set>
#include <string>

VK_DEFINE_NON_DISPATCHABLE_HANDLE(DISTINCT_NONDISPATCHABLE_PHONY_HANDLE)
// The following line must match the vulkan_core.h condition guarding VK_DEFINE_NON_DISPATCHABLE_HANDLE
#if defined(__LP64__) || defined(_WIN64) || (defined(__x86_64__) && !defined(__ILP32__)) || defined(_M_X64) || defined(__ia64) || \
    defined(_M_IA64) || defined(__aarch64__) || defined(__powerpc64__)
// If pointers are 64-bit, then there can be separate counters for each
// NONDISPATCHABLE_HANDLE type.  Otherwise they are all typedef uint64_t.
#define DISTINCT_NONDISPATCHABLE_HANDLES
// Make sure we catch any disagreement between us and the vulkan definition
static_assert(std::is_pointer<DISTINCT_NONDISPATCHABLE_PHONY_HANDLE>::value,
              "Mismatched non-dispatchable handle handle, expected pointer type.");
#else
// Make sure we catch any disagreement between us and the vulkan definition
static_assert(std::is_same<uint64_t, DISTINCT_NONDISPATCHABLE_PHONY_HANDLE>::value,
              "Mismatched non-dispatchable handle handle, expected uint64_t.");
#endif

// Suppress unused warning on Linux
#if defined(__GNUC__)
#define DECORATE_UNUSED __attribute__((unused))
#else
#define DECORATE_UNUSED
#endif

// clang-format off
static const char DECORATE_UNUSED *kVUID_Threading_Info = "UNASSIGNED-Threading-Info";
static const char DECORATE_UNUSED *kVUID_Threading_MultipleThreads = "UNASSIGNED-Threading-MultipleThreads";
static const char DECORATE_UNUSED *kVUID_Threading_SingleThreadReuse = "UNASSIGNED-Threading-SingleThreadReuse";
// clang-format on

#undef DECORATE_UNUSED

struct object_use_data {
    loader_platform_thread_id thread;
    int reader_count;
    int writer_count;
};

// This is a wrapper around unordered_map that optimizes for the common case
// of only containing a single element. The "first" element's use is stored
// inline in the class and doesn't require hashing or memory (de)allocation.
// TODO: Consider generalizing this from one element to N elements (where N
// is a template parameter).
template <typename Key, typename T>
class small_unordered_map {

    bool first_data_allocated;
    Key first_data_key;
    T first_data;

    std::unordered_map<Key, T> uses;

public:
    small_unordered_map() : first_data_allocated(false) {}

    bool contains(const Key& object) const {
        if (first_data_allocated && object == first_data_key) {
            return true;
        // check size() first to avoid hashing object unnecessarily.
        } else if (uses.size() == 0) {
            return false;
        } else {
            return uses.find(object) != uses.end();
        }
    }

    T& operator[](const Key& object) {
        if (first_data_allocated && first_data_key == object) {
            return first_data;
        } else if (!first_data_allocated && uses.size() == 0) {
            first_data_allocated = true;
            first_data_key = object;
            return first_data;
        } else {
            return uses[object];
        }
    }

    typename std::unordered_map<Key, T>::size_type erase(const Key& object) {
        if (first_data_allocated && first_data_key == object) {
            first_data_allocated = false;
            return 1;
        } else {
            return uses.erase(object);
        }
    }
};

template <typename T>
class counter {
public:
    const char *typeName;
    VkDebugReportObjectTypeEXT objectType;
    debug_report_data **report_data;
    small_unordered_map<T, object_use_data> uses;
    std::mutex counter_lock;
    std::condition_variable counter_condition;


    void StartWrite(T object) {
        if (object == VK_NULL_HANDLE) {
            return;
        }
        bool skip = false;
        loader_platform_thread_id tid = loader_platform_get_thread_id();
        std::unique_lock<std::mutex> lock(counter_lock);
        if (!uses.contains(object)) {
            // There is no current use of the object.  Record writer thread.
            struct object_use_data *use_data = &uses[object];
            use_data->reader_count = 0;
            use_data->writer_count = 1;
            use_data->thread = tid;
        } else {
            struct object_use_data *use_data = &uses[object];
            if (use_data->reader_count == 0) {
                // There are no readers.  Two writers just collided.
                if (use_data->thread != tid) {
                    skip |= log_msg(*report_data, VK_DEBUG_REPORT_ERROR_BIT_EXT, objectType, (uint64_t)(object),
                        kVUID_Threading_MultipleThreads,
                        "THREADING ERROR : object of type %s is simultaneously used in "
                        "thread 0x%" PRIx64 " and thread 0x%" PRIx64,
                        typeName, (uint64_t)use_data->thread, (uint64_t)tid);
                    if (skip) {
                        // Wait for thread-safe access to object instead of skipping call.
                        while (uses.contains(object)) {
                            counter_condition.wait(lock);
                        }
                        // There is now no current use of the object.  Record writer thread.
                        struct object_use_data *new_use_data = &uses[object];
                        new_use_data->thread = tid;
                        new_use_data->reader_count = 0;
                        new_use_data->writer_count = 1;
                    } else {
                        // Continue with an unsafe use of the object.
                        use_data->thread = tid;
                        use_data->writer_count += 1;
                    }
                } else {
                    // This is either safe multiple use in one call, or recursive use.
                    // There is no way to make recursion safe.  Just forge ahead.
                    use_data->writer_count += 1;
                }
            } else {
                // There are readers.  This writer collided with them.
                if (use_data->thread != tid) {
                    skip |= log_msg(*report_data, VK_DEBUG_REPORT_ERROR_BIT_EXT, objectType, (uint64_t)(object),
                        kVUID_Threading_MultipleThreads,
                        "THREADING ERROR : object of type %s is simultaneously used in "
                        "thread 0x%" PRIx64 " and thread 0x%" PRIx64,
                        typeName, (uint64_t)use_data->thread, (uint64_t)tid);
                    if (skip) {
                        // Wait for thread-safe access to object instead of skipping call.
                        while (uses.contains(object)) {
                            counter_condition.wait(lock);
                        }
                        // There is now no current use of the object.  Record writer thread.
                        struct object_use_data *new_use_data = &uses[object];
                        new_use_data->thread = tid;
                        new_use_data->reader_count = 0;
                        new_use_data->writer_count = 1;
                    } else {
                        // Continue with an unsafe use of the object.
                        use_data->thread = tid;
                        use_data->writer_count += 1;
                    }
                } else {
                    // This is either safe multiple use in one call, or recursive use.
                    // There is no way to make recursion safe.  Just forge ahead.
                    use_data->writer_count += 1;
                }
            }
        }
    }

    void FinishWrite(T object) {
        if (object == VK_NULL_HANDLE) {
            return;
        }
        // Object is no longer in use
        std::unique_lock<std::mutex> lock(counter_lock);
        uses[object].writer_count -= 1;
        if ((uses[object].reader_count == 0) && (uses[object].writer_count == 0)) {
            uses.erase(object);
        }
        // Notify any waiting threads that this object may be safe to use
        lock.unlock();
        counter_condition.notify_all();
    }

    void StartRead(T object) {
        if (object == VK_NULL_HANDLE) {
            return;
        }
        bool skip = false;
        loader_platform_thread_id tid = loader_platform_get_thread_id();
        std::unique_lock<std::mutex> lock(counter_lock);
        if (!uses.contains(object)) {
            // There is no current use of the object.  Record reader count
            struct object_use_data *use_data = &uses[object];
            use_data->reader_count = 1;
            use_data->writer_count = 0;
            use_data->thread = tid;
        } else if (uses[object].writer_count > 0 && uses[object].thread != tid) {
            // There is a writer of the object.
            skip |= false;
            log_msg(*report_data, VK_DEBUG_REPORT_ERROR_BIT_EXT, objectType, (uint64_t)(object), kVUID_Threading_MultipleThreads,
                "THREADING ERROR : object of type %s is simultaneously used in "
                "thread 0x%" PRIx64 " and thread 0x%" PRIx64,
                typeName, (uint64_t)uses[object].thread, (uint64_t)tid);
            if (skip) {
                // Wait for thread-safe access to object instead of skipping call.
                while (uses.contains(object)) {
                    counter_condition.wait(lock);
                }
                // There is no current use of the object.  Record reader count
                struct object_use_data *use_data = &uses[object];
                use_data->reader_count = 1;
                use_data->writer_count = 0;
                use_data->thread = tid;
            } else {
                uses[object].reader_count += 1;
            }
        } else {
            // There are other readers of the object.  Increase reader count
            uses[object].reader_count += 1;
        }
    }
    void FinishRead(T object) {
        if (object == VK_NULL_HANDLE) {
            return;
        }
        std::unique_lock<std::mutex> lock(counter_lock);
        uses[object].reader_count -= 1;
        if ((uses[object].reader_count == 0) && (uses[object].writer_count == 0)) {
            uses.erase(object);
        }
        // Notify any waiting threads that this object may be safe to use
        lock.unlock();
        counter_condition.notify_all();
    }
    counter(const char *name = "", VkDebugReportObjectTypeEXT type = VK_DEBUG_REPORT_OBJECT_TYPE_UNKNOWN_EXT, debug_report_data **rep_data = nullptr) {
        typeName = name;
        objectType = type;
        report_data = rep_data;
    }
};



class ThreadSafety : public ValidationObject {
public:

    // Override chassis read/write locks for this validation object
    // This override takes a deferred lock. i.e. it is not acquired.
    std::unique_lock<std::mutex> write_lock() {
        return std::unique_lock<std::mutex>(validation_object_mutex, std::defer_lock);
    }

    std::mutex command_pool_lock;
    std::unordered_map<VkCommandBuffer, VkCommandPool> command_pool_map;

    counter<VkCommandBuffer> c_VkCommandBuffer;
    counter<VkDevice> c_VkDevice;
    counter<VkInstance> c_VkInstance;
    counter<VkQueue> c_VkQueue;
#ifdef DISTINCT_NONDISPATCHABLE_HANDLES

    // Special entry to allow tracking of command pool Reset and Destroy
    counter<VkCommandPool> c_VkCommandPoolContents;
COUNTER_CLASS_DEFINITIONS_TEMPLATE

#else   // DISTINCT_NONDISPATCHABLE_HANDLES
    // Special entry to allow tracking of command pool Reset and Destroy
    counter<uint64_t> c_VkCommandPoolContents;

    counter<uint64_t> c_uint64_t;
#endif  // DISTINCT_NONDISPATCHABLE_HANDLES

    ThreadSafety()
        : c_VkCommandBuffer("VkCommandBuffer", VK_DEBUG_REPORT_OBJECT_TYPE_COMMAND_BUFFER_EXT, &report_data),
          c_VkDevice("VkDevice", VK_DEBUG_REPORT_OBJECT_TYPE_DEVICE_EXT, &report_data),
          c_VkInstance("VkInstance", VK_DEBUG_REPORT_OBJECT_TYPE_INSTANCE_EXT, &report_data),
          c_VkQueue("VkQueue", VK_DEBUG_REPORT_OBJECT_TYPE_QUEUE_EXT, &report_data),
          c_VkCommandPoolContents("VkCommandPool", VK_DEBUG_REPORT_OBJECT_TYPE_COMMAND_POOL_EXT, &report_data),

#ifdef DISTINCT_NONDISPATCHABLE_HANDLES
COUNTER_CLASS_INSTANCES_TEMPLATE


#else   // DISTINCT_NONDISPATCHABLE_HANDLES
          c_uint64_t("NON_DISPATCHABLE_HANDLE", VK_DEBUG_REPORT_OBJECT_TYPE_UNKNOWN_EXT, &report_data)
#endif  // DISTINCT_NONDISPATCHABLE_HANDLES
              {};

#define WRAPPER(type)                                                \
    void StartWriteObject(type object) {                             \
        c_##type.StartWrite(object);                                 \
    }                                                                \
    void FinishWriteObject(type object) {                            \
        c_##type.FinishWrite(object);                                \
    }                                                                \
    void StartReadObject(type object) {                              \
        c_##type.StartRead(object);                                  \
    }                                                                \
    void FinishReadObject(type object) {                             \
        c_##type.FinishRead(object);                                 \
    }

WRAPPER(VkDevice)
WRAPPER(VkInstance)
WRAPPER(VkQueue)
#ifdef DISTINCT_NONDISPATCHABLE_HANDLES
COUNTER_CLASS_BODIES_TEMPLATE

#else   // DISTINCT_NONDISPATCHABLE_HANDLES
WRAPPER(uint64_t)
#endif  // DISTINCT_NONDISPATCHABLE_HANDLES

    // VkCommandBuffer needs check for implicit use of command pool
    void StartWriteObject(VkCommandBuffer object, bool lockPool = true) {
        if (lockPool) {
            std::unique_lock<std::mutex> lock(command_pool_lock);
            VkCommandPool pool = command_pool_map[object];
            lock.unlock();
            StartWriteObject(pool);
        }
        c_VkCommandBuffer.StartWrite(object);
    }
    void FinishWriteObject(VkCommandBuffer object, bool lockPool = true) {
        c_VkCommandBuffer.FinishWrite(object);
        if (lockPool) {
            std::unique_lock<std::mutex> lock(command_pool_lock);
            VkCommandPool pool = command_pool_map[object];
            lock.unlock();
            FinishWriteObject(pool);
        }
    }
    void StartReadObject(VkCommandBuffer object) {
        std::unique_lock<std::mutex> lock(command_pool_lock);
        VkCommandPool pool = command_pool_map[object];
        lock.unlock();
        // We set up a read guard against the "Contents" counter to catch conflict vs. vkResetCommandPool and vkDestroyCommandPool
        // while *not* establishing a read guard against the command pool counter itself to avoid false postives for
        // non-externally sync'd command buffers
        c_VkCommandPoolContents.StartRead(pool);
        c_VkCommandBuffer.StartRead(object);
    }
    void FinishReadObject(VkCommandBuffer object) {
        c_VkCommandBuffer.FinishRead(object);
        std::unique_lock<std::mutex> lock(command_pool_lock);
        VkCommandPool pool = command_pool_map[object];
        lock.unlock();
        c_VkCommandPoolContents.FinishRead(pool);
    } """


    inline_custom_source_preamble = """
void ThreadSafety::PreCallRecordAllocateCommandBuffers(VkDevice device, const VkCommandBufferAllocateInfo *pAllocateInfo,
                                                       VkCommandBuffer *pCommandBuffers) {
    StartReadObject(device);
    StartWriteObject(pAllocateInfo->commandPool);
}

void ThreadSafety::PostCallRecordAllocateCommandBuffers(VkDevice device, const VkCommandBufferAllocateInfo *pAllocateInfo,
                                                        VkCommandBuffer *pCommandBuffers, VkResult result) {
    FinishReadObject(device);
    FinishWriteObject(pAllocateInfo->commandPool);

    // Record mapping from command buffer to command pool
    if(pCommandBuffers) {
        std::lock_guard<std::mutex> lock(command_pool_lock);
        for (uint32_t index = 0; index < pAllocateInfo->commandBufferCount; index++) {
            command_pool_map[pCommandBuffers[index]] = pAllocateInfo->commandPool;
        }
    }
}

void ThreadSafety::PreCallRecordAllocateDescriptorSets(VkDevice device, const VkDescriptorSetAllocateInfo *pAllocateInfo,
                                                       VkDescriptorSet *pDescriptorSets) {
    StartReadObject(device);
    StartWriteObject(pAllocateInfo->descriptorPool);
    // Host access to pAllocateInfo::descriptorPool must be externally synchronized
}

void ThreadSafety::PostCallRecordAllocateDescriptorSets(VkDevice device, const VkDescriptorSetAllocateInfo *pAllocateInfo,
                                                        VkDescriptorSet *pDescriptorSets, VkResult result) {
    FinishReadObject(device);
    FinishWriteObject(pAllocateInfo->descriptorPool);
    // Host access to pAllocateInfo::descriptorPool must be externally synchronized
}

void ThreadSafety::PreCallRecordFreeCommandBuffers(VkDevice device, VkCommandPool commandPool, uint32_t commandBufferCount,
                                                   const VkCommandBuffer *pCommandBuffers) {
    const bool lockCommandPool = false;  // pool is already directly locked
    StartReadObject(device);
    StartWriteObject(commandPool);
    if(pCommandBuffers) {
        // Even though we're immediately "finishing" below, we still are testing for concurrency with any call in process
        // so this isn't a no-op
        for (uint32_t index = 0; index < commandBufferCount; index++) {
            StartWriteObject(pCommandBuffers[index], lockCommandPool);
        }
        // The driver may immediately reuse command buffers in another thread.
        // These updates need to be done before calling down to the driver.
        for (uint32_t index = 0; index < commandBufferCount; index++) {
            FinishWriteObject(pCommandBuffers[index], lockCommandPool);
        }
        // Holding the lock for the shortest time while we update the map
        std::lock_guard<std::mutex> lock(command_pool_lock);
        for (uint32_t index = 0; index < commandBufferCount; index++) {
            command_pool_map.erase(pCommandBuffers[index]);
        }
    }
}

void ThreadSafety::PostCallRecordFreeCommandBuffers(VkDevice device, VkCommandPool commandPool, uint32_t commandBufferCount,
                                                    const VkCommandBuffer *pCommandBuffers) {
    FinishReadObject(device);
    FinishWriteObject(commandPool);
}

void ThreadSafety::PreCallRecordResetCommandPool(VkDevice device, VkCommandPool commandPool, VkCommandPoolResetFlags flags) {
    StartReadObject(device);
    StartWriteObject(commandPool);
    // Check for any uses of non-externally sync'd command buffers (for example from vkCmdExecuteCommands)
    c_VkCommandPoolContents.StartWrite(commandPool);
    // Host access to commandPool must be externally synchronized
}

void ThreadSafety::PostCallRecordResetCommandPool(VkDevice device, VkCommandPool commandPool, VkCommandPoolResetFlags flags, VkResult result) {
    FinishReadObject(device);
    FinishWriteObject(commandPool);
    c_VkCommandPoolContents.FinishWrite(commandPool);
    // Host access to commandPool must be externally synchronized
}

void ThreadSafety::PreCallRecordDestroyCommandPool(VkDevice device, VkCommandPool commandPool, const VkAllocationCallbacks *pAllocator) {
    StartReadObject(device);
    StartWriteObject(commandPool);
    // Check for any uses of non-externally sync'd command buffers (for example from vkCmdExecuteCommands)
    c_VkCommandPoolContents.StartWrite(commandPool);
    // Host access to commandPool must be externally synchronized
}

void ThreadSafety::PostCallRecordDestroyCommandPool(VkDevice device, VkCommandPool commandPool, const VkAllocationCallbacks *pAllocator) {
    FinishReadObject(device);
    FinishWriteObject(commandPool);
    c_VkCommandPoolContents.FinishWrite(commandPool);
}

// GetSwapchainImages can return a non-zero count with a NULL pSwapchainImages pointer.  Let's avoid crashes by ignoring
// pSwapchainImages.
void ThreadSafety::PreCallRecordGetSwapchainImagesKHR(VkDevice device, VkSwapchainKHR swapchain, uint32_t *pSwapchainImageCount,
                                                      VkImage *pSwapchainImages) {
    StartReadObject(device);
    StartReadObject(swapchain);
}

void ThreadSafety::PostCallRecordGetSwapchainImagesKHR(VkDevice device, VkSwapchainKHR swapchain, uint32_t *pSwapchainImageCount,
                                                       VkImage *pSwapchainImages, VkResult result) {
    FinishReadObject(device);
    FinishReadObject(swapchain);
}

"""


    # This is an ordered list of sections in the header file.
    ALL_SECTIONS = ['command']
    def __init__(self,
                 errFile = sys.stderr,
                 warnFile = sys.stderr,
                 diagFile = sys.stdout):
        OutputGenerator.__init__(self, errFile, warnFile, diagFile)
        # Internal state - accumulators for different inner block text
        self.sections = dict([(section, []) for section in self.ALL_SECTIONS])
        self.non_dispatchable_types = set()
        self.object_to_debug_report_type = {
            'VkInstance' : 'VK_DEBUG_REPORT_OBJECT_TYPE_INSTANCE_EXT',
            'VkPhysicalDevice' : 'VK_DEBUG_REPORT_OBJECT_TYPE_PHYSICAL_DEVICE_EXT',
            'VkDevice' : 'VK_DEBUG_REPORT_OBJECT_TYPE_DEVICE_EXT',
            'VkQueue' : 'VK_DEBUG_REPORT_OBJECT_TYPE_QUEUE_EXT',
            'VkSemaphore' : 'VK_DEBUG_REPORT_OBJECT_TYPE_SEMAPHORE_EXT',
            'VkCommandBuffer' : 'VK_DEBUG_REPORT_OBJECT_TYPE_COMMAND_BUFFER_EXT',
            'VkFence' : 'VK_DEBUG_REPORT_OBJECT_TYPE_FENCE_EXT',
            'VkDeviceMemory' : 'VK_DEBUG_REPORT_OBJECT_TYPE_DEVICE_MEMORY_EXT',
            'VkBuffer' : 'VK_DEBUG_REPORT_OBJECT_TYPE_BUFFER_EXT',
            'VkImage' : 'VK_DEBUG_REPORT_OBJECT_TYPE_IMAGE_EXT',
            'VkEvent' : 'VK_DEBUG_REPORT_OBJECT_TYPE_EVENT_EXT',
            'VkQueryPool' : 'VK_DEBUG_REPORT_OBJECT_TYPE_QUERY_POOL_EXT',
            'VkBufferView' : 'VK_DEBUG_REPORT_OBJECT_TYPE_BUFFER_VIEW_EXT',
            'VkImageView' : 'VK_DEBUG_REPORT_OBJECT_TYPE_IMAGE_VIEW_EXT',
            'VkShaderModule' : 'VK_DEBUG_REPORT_OBJECT_TYPE_SHADER_MODULE_EXT',
            'VkPipelineCache' : 'VK_DEBUG_REPORT_OBJECT_TYPE_PIPELINE_CACHE_EXT',
            'VkPipelineLayout' : 'VK_DEBUG_REPORT_OBJECT_TYPE_PIPELINE_LAYOUT_EXT',
            'VkRenderPass' : 'VK_DEBUG_REPORT_OBJECT_TYPE_RENDER_PASS_EXT',
            'VkPipeline' : 'VK_DEBUG_REPORT_OBJECT_TYPE_PIPELINE_EXT',
            'VkDescriptorSetLayout' : 'VK_DEBUG_REPORT_OBJECT_TYPE_DESCRIPTOR_SET_LAYOUT_EXT',
            'VkSampler' : 'VK_DEBUG_REPORT_OBJECT_TYPE_SAMPLER_EXT',
            'VkDescriptorPool' : 'VK_DEBUG_REPORT_OBJECT_TYPE_DESCRIPTOR_POOL_EXT',
            'VkDescriptorSet' : 'VK_DEBUG_REPORT_OBJECT_TYPE_DESCRIPTOR_SET_EXT',
            'VkFramebuffer' : 'VK_DEBUG_REPORT_OBJECT_TYPE_FRAMEBUFFER_EXT',
            'VkCommandPool' : 'VK_DEBUG_REPORT_OBJECT_TYPE_COMMAND_POOL_EXT',
            'VkSurfaceKHR' : 'VK_DEBUG_REPORT_OBJECT_TYPE_SURFACE_KHR_EXT',
            'VkSwapchainKHR' : 'VK_DEBUG_REPORT_OBJECT_TYPE_SWAPCHAIN_KHR_EXT',
            'VkDisplayKHR' : 'VK_DEBUG_REPORT_OBJECT_TYPE_DISPLAY_KHR_EXT',
            'VkDisplayModeKHR' : 'VK_DEBUG_REPORT_OBJECT_TYPE_DISPLAY_MODE_KHR_EXT',
            'VkObjectTableNVX' : 'VK_DEBUG_REPORT_OBJECT_TYPE_OBJECT_TABLE_NVX_EXT',
            'VkIndirectCommandsLayoutNVX' : 'VK_DEBUG_REPORT_OBJECT_TYPE_INDIRECT_COMMANDS_LAYOUT_NVX_EXT',
            'VkSamplerYcbcrConversion' : 'VK_DEBUG_REPORT_OBJECT_TYPE_SAMPLER_YCBCR_CONVERSION_EXT',
            'VkDescriptorUpdateTemplate' : 'VK_DEBUG_REPORT_OBJECT_TYPE_DESCRIPTOR_UPDATE_TEMPLATE_EXT',
            'VkAccelerationStructureNV' : 'VK_DEBUG_REPORT_OBJECT_TYPE_ACCELERATION_STRUCTURE_NV_EXT',
            'VkDebugReportCallbackEXT' : 'VK_DEBUG_REPORT_OBJECT_TYPE_DEBUG_REPORT_EXT',
            'VkValidationCacheEXT' : 'VK_DEBUG_REPORT_OBJECT_TYPE_VALIDATION_CACHE_EXT' }

    # Check if the parameter passed in is a pointer to an array
    def paramIsArray(self, param):
        return param.attrib.get('len') is not None

    # Check if the parameter passed in is a pointer
    def paramIsPointer(self, param):
        ispointer = False
        for elem in param:
            if elem.tag == 'type' and elem.tail is not None and '*' in elem.tail:
                ispointer = True
        return ispointer

    # Check if an object is a non-dispatchable handle
    def isHandleTypeNonDispatchable(self, handletype):
        handle = self.registry.tree.find("types/type/[name='" + handletype + "'][@category='handle']")
        if handle is not None and handle.find('type').text == 'VK_DEFINE_NON_DISPATCHABLE_HANDLE':
            return True
        else:
            return False

    # Check if an object is a dispatchable handle
    def isHandleTypeDispatchable(self, handletype):
        handle = self.registry.tree.find("types/type/[name='" + handletype + "'][@category='handle']")
        if handle is not None and handle.find('type').text == 'VK_DEFINE_HANDLE':
            return True
        else:
            return False

    def makeThreadUseBlock(self, cmd, functionprefix):
        """Generate C function pointer typedef for <command> Element"""
        paramdecl = ''
        # Find and add any parameters that are thread unsafe
        params = cmd.findall('param')
        for param in params:
            paramname = param.find('name')
            if False: # self.paramIsPointer(param):
                paramdecl += '    // not watching use of pointer ' + paramname.text + '\n'
            else:
                externsync = param.attrib.get('externsync')
                if externsync == 'true':
                    if self.paramIsArray(param):
                        paramdecl += 'if (' + paramname.text + ') {\n'
                        paramdecl += '    for (uint32_t index=0; index < ' + param.attrib.get('len') + '; index++) {\n'
                        paramdecl += '        ' + functionprefix + 'WriteObject(' + paramname.text + '[index]);\n'
                        paramdecl += '    }\n'
                        paramdecl += '}\n'
                    else:
                        paramdecl += functionprefix + 'WriteObject(' + paramname.text + ');\n'
                elif (param.attrib.get('externsync')):
                    if self.paramIsArray(param):
                        # Externsync can list pointers to arrays of members to synchronize
                        paramdecl += 'if (' + paramname.text + ') {\n'
                        paramdecl += '    for (uint32_t index=0; index < ' + param.attrib.get('len') + '; index++) {\n'
                        second_indent = '    '
                        for member in externsync.split(","):
                            # Replace first empty [] in member name with index
                            element = member.replace('[]','[index]',1)
                            if '[]' in element:
                                # TODO: These null checks can be removed if threading ends up behind parameter
                                #       validation in layer order
                                element_ptr = element.split('[]')[0]
                                paramdecl += '        if (' + element_ptr + ') {\n'
                                # Replace any second empty [] in element name with inner array index based on mapping array
                                # names like "pSomeThings[]" to "someThingCount" array size. This could be more robust by
                                # mapping a param member name to a struct type and "len" attribute.
                                limit = element[0:element.find('s[]')] + 'Count'
                                dotp = limit.rfind('.p')
                                limit = limit[0:dotp+1] + limit[dotp+2:dotp+3].lower() + limit[dotp+3:]
                                paramdecl += '            for (uint32_t index2=0; index2 < '+limit+'; index2++) {\n'
                                element = element.replace('[]','[index2]')
                                second_indent = '        '
                                paramdecl += '        ' + second_indent + functionprefix + 'WriteObject(' + element + ');\n'
                                paramdecl += '            }\n'
                                paramdecl += '        }\n'
                            else:
                                paramdecl += '    ' + second_indent + functionprefix + 'WriteObject(' + element + ');\n'
                        paramdecl += '    }\n'
                        paramdecl += '}\n'
                    else:
                        # externsync can list members to synchronize
                        for member in externsync.split(","):
                            member = str(member).replace("::", "->")
                            member = str(member).replace(".", "->")
                            paramdecl += '    ' + functionprefix + 'WriteObject(' + member + ');\n'
                else:
                    paramtype = param.find('type')
                    if paramtype is not None:
                        paramtype = paramtype.text
                    else:
                        paramtype = 'None'
                    if (self.isHandleTypeDispatchable(paramtype) or self.isHandleTypeNonDispatchable(paramtype)) and paramtype != 'VkPhysicalDevice':
                        if self.paramIsArray(param) and ('pPipelines' != paramname.text):
                            # Add pointer dereference for array counts that are pointer values
                            dereference = ''
                            for candidate in params:
                                if param.attrib.get('len') == candidate.find('name').text:
                                    if self.paramIsPointer(candidate):
                                        dereference = '*'
                            param_len = str(param.attrib.get('len')).replace("::", "->")
                            paramdecl += 'if (' + paramname.text + ') {\n'
                            paramdecl += '    for (uint32_t index = 0; index < ' + dereference + param_len + '; index++) {\n'
                            paramdecl += '        ' + functionprefix + 'ReadObject(' + paramname.text + '[index]);\n'
                            paramdecl += '    }\n'
                            paramdecl += '}\n'
                        elif not self.paramIsPointer(param):
                            # Pointer params are often being created.
                            # They are not being read from.
                            paramdecl += functionprefix + 'ReadObject(' + paramname.text + ');\n'
        explicitexternsyncparams = cmd.findall("param[@externsync]")
        if (explicitexternsyncparams is not None):
            for param in explicitexternsyncparams:
                externsyncattrib = param.attrib.get('externsync')
                paramname = param.find('name')
                paramdecl += '// Host access to '
                if externsyncattrib == 'true':
                    if self.paramIsArray(param):
                        paramdecl += 'each member of ' + paramname.text
                    elif self.paramIsPointer(param):
                        paramdecl += 'the object referenced by ' + paramname.text
                    else:
                        paramdecl += paramname.text
                else:
                    paramdecl += externsyncattrib
                paramdecl += ' must be externally synchronized\n'

        # Find and add any "implicit" parameters that are thread unsafe
        implicitexternsyncparams = cmd.find('implicitexternsyncparams')
        if (implicitexternsyncparams is not None):
            for elem in implicitexternsyncparams:
                paramdecl += '// '
                paramdecl += elem.text
                paramdecl += ' must be externally synchronized between host accesses\n'

        if (paramdecl == ''):
            return None
        else:
            return paramdecl
    def beginFile(self, genOpts):
        OutputGenerator.beginFile(self, genOpts)
        #
        # TODO: LUGMAL -- remove this and add our copyright
        # User-supplied prefix text, if any (list of strings)
        write(self.inline_copyright_message, file=self.outFile)

        self.header_file = (genOpts.filename == 'thread_safety.h')
        self.source_file = (genOpts.filename == 'thread_safety.cpp')

        if not self.header_file and not self.source_file:
            print("Error: Output Filenames have changed, update generator source.\n")
            sys.exit(1)

        if self.source_file:
            write('#include "chassis.h"', file=self.outFile)
            write('#include "thread_safety.h"', file=self.outFile)
            self.newline()
            write(self.inline_custom_source_preamble, file=self.outFile)


    def endFile(self):

        # Create class definitions
        counter_class_defs = ''
        counter_class_instances = ''
        counter_class_bodies = ''

        for obj in self.non_dispatchable_types:
            counter_class_defs += '    counter<%s> c_%s;\n' % (obj, obj)
            if obj in self.object_to_debug_report_type:
                obj_type = self.object_to_debug_report_type[obj]
            else:
                obj_type = 'VK_DEBUG_REPORT_OBJECT_TYPE_UNKNOWN_EXT'
            counter_class_instances += '          c_%s("%s", %s, &report_data),\n' % (obj, obj, obj_type)
            counter_class_bodies += 'WRAPPER(%s)\n' % obj
        if self.header_file:
            class_def = self.inline_custom_header_preamble.replace('COUNTER_CLASS_DEFINITIONS_TEMPLATE', counter_class_defs)
            class_def = class_def.replace('COUNTER_CLASS_INSTANCES_TEMPLATE', counter_class_instances[:-2]) # Kill last comma
            class_def = class_def.replace('COUNTER_CLASS_BODIES_TEMPLATE', counter_class_bodies)
            write(class_def, file=self.outFile)
        write('\n'.join(self.sections['command']), file=self.outFile)
        if self.header_file:
            write('};', file=self.outFile)

        # Finish processing in superclass
        OutputGenerator.endFile(self)

    def beginFeature(self, interface, emit):
        #write('// starting beginFeature', file=self.outFile)
        # Start processing in superclass
        OutputGenerator.beginFeature(self, interface, emit)
        # C-specific
        # Accumulate includes, defines, types, enums, function pointer typedefs,
        # end function prototypes separately for this feature. They're only
        # printed in endFeature().
        self.featureExtraProtect = GetFeatureProtect(interface)
        if (self.featureExtraProtect is not None):
            self.appendSection('command', '\n#ifdef %s' % self.featureExtraProtect)

        #write('// ending beginFeature', file=self.outFile)
    def endFeature(self):
        # C-specific
        if (self.emit):
            if (self.featureExtraProtect is not None):
                self.appendSection('command', '#endif // %s' % self.featureExtraProtect)
        # Finish processing in superclass
        OutputGenerator.endFeature(self)
    #
    # Append a definition to the specified section
    def appendSection(self, section, text):
        self.sections[section].append(text)
    #
    # Type generation
    def genType(self, typeinfo, name, alias):
        OutputGenerator.genType(self, typeinfo, name, alias)
        type_elem = typeinfo.elem
        category = type_elem.get('category')
        if category == 'handle':
            if self.isHandleTypeNonDispatchable(name):
                self.non_dispatchable_types.add(name)
    #
    # Struct (e.g. C "struct" type) generation.
    # This is a special case of the <type> tag where the contents are
    # interpreted as a set of <member> tags instead of freeform C
    # C type declarations. The <member> tags are just like <param>
    # tags - they are a declaration of a struct or union member.
    # Only simple member declarations are supported (no nested
    # structs etc.)
    def genStruct(self, typeinfo, typeName, alias):
        OutputGenerator.genStruct(self, typeinfo, typeName, alias)
        body = 'typedef ' + typeinfo.elem.get('category') + ' ' + typeName + ' {\n'
        # paramdecl = self.makeCParamDecl(typeinfo.elem, self.genOpts.alignFuncParam)
        for member in typeinfo.elem.findall('.//member'):
            body += self.makeCParamDecl(member, self.genOpts.alignFuncParam)
            body += ';\n'
        body += '} ' + typeName + ';\n'
        self.appendSection('struct', body)
    #
    # Group (e.g. C "enum" type) generation.
    # These are concatenated together with other types.
    def genGroup(self, groupinfo, groupName, alias):
        pass
    # Enumerant generation
    # <enum> tags may specify their values in several ways, but are usually
    # just integers.
    def genEnum(self, enuminfo, name, alias):
        pass
    #
    # Command generation
    def genCmd(self, cmdinfo, name, alias):
        # Commands shadowed by interface functions and are not implemented
        special_functions = [
            'vkCreateDevice',
            'vkCreateInstance',
            'vkAllocateCommandBuffers',
            'vkFreeCommandBuffers',
            'vkResetCommandPool',
            'vkDestroyCommandPool',
            'vkAllocateDescriptorSets',
            'vkQueuePresentKHR',
            'vkGetSwapchainImagesKHR',
        ]
        if name == 'vkQueuePresentKHR' or (name in special_functions and self.source_file):
            return

        if (("DebugMarker" in name or "DebugUtilsObject" in name) and "EXT" in name):
            self.appendSection('command', '// TODO - not wrapping EXT function ' + name)
            return

        # Determine first if this function needs to be intercepted
        startthreadsafety = self.makeThreadUseBlock(cmdinfo.elem, 'Start')
        if startthreadsafety is None:
            return
        finishthreadsafety = self.makeThreadUseBlock(cmdinfo.elem, 'Finish')

        OutputGenerator.genCmd(self, cmdinfo, name, alias)

        # setup common to call wrappers
        # first parameter is always dispatchable
        dispatchable_type = cmdinfo.elem.find('param/type').text
        dispatchable_name = cmdinfo.elem.find('param/name').text

        decls = self.makeCDecls(cmdinfo.elem)

        result_type = cmdinfo.elem.find('proto/type')

        if self.source_file:
            pre_decl = decls[0][:-1]
            pre_decl = pre_decl.split("VKAPI_CALL ")[1]
            pre_decl = 'void ThreadSafety::PreCallRecord' + pre_decl + ' {'

            # PreCallRecord
            self.appendSection('command', '')
            self.appendSection('command', pre_decl)
            self.appendSection('command', "    " + "\n    ".join(str(startthreadsafety).rstrip().split("\n")))
            self.appendSection('command', '}')

            # PostCallRecord
            post_decl = pre_decl.replace('PreCallRecord', 'PostCallRecord')
            if result_type.text == 'VkResult':
                post_decl = post_decl.replace(')', ',\n    VkResult                                    result)')
            self.appendSection('command', '')
            self.appendSection('command', post_decl)
            self.appendSection('command', "    " + "\n    ".join(str(finishthreadsafety).rstrip().split("\n")))
            self.appendSection('command', '}')

        if self.header_file:
            pre_decl = decls[0][:-1]
            pre_decl = pre_decl.split("VKAPI_CALL ")[1]
            pre_decl = 'void PreCallRecord' + pre_decl + ';'

            # PreCallRecord
            self.appendSection('command', '')
            self.appendSection('command', pre_decl)

            # PostCallRecord
            post_decl = pre_decl.replace('PreCallRecord', 'PostCallRecord')
            if result_type.text == 'VkResult':
                post_decl = post_decl.replace(')', ',\n    VkResult                                    result)')
            self.appendSection('command', '')
            self.appendSection('command', post_decl)

    #
    # override makeProtoName to drop the "vk" prefix
    def makeProtoName(self, name, tail):
        return self.genOpts.apientry + name[2:] + tail