/*****************************************************************************

Copyright 2018 The TensorFlow.NET Authors. All Rights Reserved.

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.

******************************************************************************/

using System;

using System.Diagnostics;

using System.Linq;

using Tensorflow.Eager;

using static Tensorflow.Binding;

using Google.Protobuf;

using Tensorflow.Util;

using Tensorflow.NumPy;

namespace Tensorflow.Contexts

{

/// <summary>

/// Environment in which eager operations execute.

/// </summary>

public sealed partial class Context

{

public const int GRAPH_MODE = 0;

public const int EAGER_MODE = 1;

int defaultExecutionMode = EAGER_MODE;

public string ScopeName { get; set; } = "";

bool initialized = false;

ContextSwitchStack context_switches;

protected FunctionCallOptions _function_call_options;

public FunctionCallOptions FunctionCallOptions

{

get

{

if(_function_call_options is null)

{

var config = Config;

_function_call_options = new FunctionCallOptions()

{

Config = config

};

}

return _function_call_options;

}

set

{

_function_call_options = value;

}

}

SafeContextHandle _handle;

int? _seed;

Random _rng;

public Context()

{

_device_policy = ContextDevicePlacementPolicy.DEVICE_PLACEMENT_SILENT;

context_switches = new ContextSwitchStack(defaultExecutionMode == EAGER_MODE, false);

initialized = false;

FunctionCallOptions = new FunctionCallOptions();

ensure_initialized();

}

/// <summary>

/// Initialize handle and devices if not already done so.

/// </summary>

public void ensure_initialized()

{

if (initialized)

return;

Debug.Assert(_context_devices is null);

Config = MergeConfig();

FunctionCallOptions.Config = Config;

var config_str = Config.ToByteArray();

var opts = new ContextOptions();

var status = new Status();

c_api.TFE_ContextOptionsSetConfig(opts, config_str, (ulong)config_str.Length, status);

status.Check(true);

c_api.TFE_ContextOptionsSetDevicePlacementPolicy(opts, _device_policy);

_handle = c_api.TFE_NewContext(opts, status);

status.Check(true);

_initialize_logical_devices();

initialized = true;

}

public void set_global_seed(int? seed)

{

_seed = seed;

if (seed.HasValue)

_rng = new Random(seed.Value);

else

_rng = null;

// Also clear the kernel cache, to reset any existing seeds

if (_handle != null)

c_api.TFE_ContextClearCaches(_handle);

}

public int? global_seed()

=> _seed;

public int? internal_operation_seed()

=> _rng?.Next(0, int.MaxValue);

public void start_step()

=> c_api.TFE_ContextStartStep(_handle);

public void end_step()

=> c_api.TFE_ContextEndStep(_handle);

/// <summary>

/// Checks whether the current thread has eager execution enabled.

/// </summary>

/// <returns></returns>

[DebuggerStepThrough]

public bool executing_eagerly()

{

if(context_switches.Count() == 0)

tf.enable_eager_execution();

return context_switches.Current().EagerMode;

}

public bool is_build_function()

=> context_switches.Current().IsBuildingFunction;

public string shared_name(string name = null)

=> !string.IsNullOrEmpty(name) || !executing_eagerly() ?

name :

"cd2c89b7-88b7-44c8-ad83-06c2a9158347";

public string anonymous_name()

{

return "cd2c89b7-88b7-44c8-ad83-06c2a9158347";

}

public void graph_mode(bool isFunc = false)

=> context_switches.Push(false, isFunc);

public void eager_mode(bool isFunc = false)

=> context_switches.Push(true, isFunc);

public bool switched_to_graph(params object[] args)

{

var switching_to_graph = has_graph_arg(args) && tf.Context.executing_eagerly();

if (switching_to_graph)

tf.Context.graph_mode(tf.Context.is_build_function());

return switching_to_graph;

}

public bool has_graph_arg(params object[] args)

{

var flatten_args = nest.flatten<object>(args);

/*if (flatten_args.Count(x => x.GetType().IsValueType) == flatten_args.Count())

return tf.Context.executing_eagerly() == false*/

bool has_graph_arg = !tf.Context.executing_eagerly();

foreach (var el in flatten_args)

{

if (el is NDArray)

continue;

else if (el is EagerTensor)

continue;

else if (el is Tensor)

{

has_graph_arg = true;

break;

}

}

return has_graph_arg;

}

public bool has_function(string name)

{

ensure_initialized();

return c_api.TFE_ContextHasFunction(_handle, name);

}

public void add_function(SafeFuncGraphHandle fn)

{

ensure_initialized();

Status status = new();

c_api.TFE_ContextAddFunction(_handle, fn, status);

status.Check(true);

}

public void remove_function(string name)

{

ensure_initialized();

Status status = new();

c_api.TFE_ContextRemoveFunction(_handle, name, status);

status.Check(true);

}

public void add_function_def(FunctionDef fdef)

{

ensure_initialized();

var fdef_string = fdef.ToByteArray();

Status status = new Status();

c_api.TFE_ContextAddFunctionDef(_handle, fdef_string, (ulong)fdef_string.Length, status);

status.Check(true);

}

public void restore_mode()

{

context_switches.Pop();

tf.get_default_graph();

}

public void reset_context()

{

// ops.reset_uid();

// tf.defaultSession = null;

ops.reset_default_graph();

context_switches.Clear();

tf.Context.ensure_initialized();

if (_handle != null)

{

c_api.TFE_ContextClearCaches(_handle);

}

_device_parsing_cache.Clear();

}

public static implicit operator SafeContextHandle(Context ctx)

{

return ctx._handle;

}

}

}