// Licensed to the Apache Software Foundation (ASF) under one

// or more contributor license agreements.  See the NOTICE file

// distributed with this work for additional information

// regarding copyright ownership.  The ASF licenses this file

// to you 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.

// bthread - An M:N threading library to make applications more concurrent.

// Date: Sun Sep  7 22:37:39 CST 2014

#ifndef BTHREAD_ALLOCATE_STACK_H

#define BTHREAD_ALLOCATE_STACK_H

#include <assert.h>

#include <gflags/gflags.h>          // DECLARE_int32

#include "bthread/types.h"

#include "bthread/context.h"        // bthread_fcontext_t

#include "butil/object_pool.h"

namespace bthread {

struct StackStorage {

     unsigned stacksize;

     unsigned guardsize;

    // Assume stack grows upwards.

    // http://www.boost.org/doc/libs/1_55_0/libs/context/doc/html/context/stack.html

    void* bottom;

    unsigned valgrind_stack_id;

    // Clears all members.

    void zeroize() {

        stacksize = 0;

        guardsize = 0;

        bottom = NULL;

        valgrind_stack_id = 0;

    }

};

// Allocate a piece of stack.

int allocate_stack_storage(StackStorage* s, int stacksize, int guardsize);

// Deallocate a piece of stack. Parameters MUST be returned or set by the

// corresponding allocate_stack_storage() otherwise behavior is undefined.

void deallocate_stack_storage(StackStorage* s);

enum StackType {

    STACK_TYPE_MAIN = 0,

    STACK_TYPE_PTHREAD = BTHREAD_STACKTYPE_PTHREAD,

    STACK_TYPE_SMALL = BTHREAD_STACKTYPE_SMALL,

    STACK_TYPE_NORMAL = BTHREAD_STACKTYPE_NORMAL,

    STACK_TYPE_LARGE = BTHREAD_STACKTYPE_LARGE

};

struct ContextualStack {

    virtual ~ContextualStack() = default;

    bthread_fcontext_t context;

    StackType stacktype;

    StackStorage storage;

};

// Get a stack in the `type' and run `entry' at the first time that the

// stack is jumped.

ContextualStack* get_stack(StackType type, void (*entry)(intptr_t));

// Recycle a stack. NULL does nothing.

void return_stack(ContextualStack*);

// Jump from stack `from' to stack `to'. `from' must be the stack of callsite

// (to save contexts before jumping)

void jump_stack(ContextualStack* from, ContextualStack* to);

}  // namespace bthread

#include "bthread/stack_inl.h"

#endif  // BTHREAD_ALLOCATE_STACK_H