/****************************************************************************
 *
 *  MODULE:     iostream
 *

 *  COPYRIGHT (C) 2007 Laura Toma
 *
 *

 *  Iostream is a library that implements streams, external memory
 *  sorting on streams, and an external memory priority queue on
 *  streams. These are the fundamental components used in external
 *  memory algorithms.

 * Credits: The library was developed by Laura Toma.  The kernel of
 * class STREAM is based on the similar class existent in the GPL TPIE
 * project developed at Duke University. The sorting and priority
 * queue have been developed by Laura Toma based on communications
 * with Rajiv Wickremesinghe. The library was developed as part of
 * porting Terraflow to GRASS in 2001.  PEARL upgrades in 2003 by
 * Rajiv Wickremesinghe as part of the Terracost project.

 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *

 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  General Public License for more details.  *
 *  **************************************************************************/

// A simple registration based memory manager.

#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#include <iostream>
using std::cerr;
using std::cout;
using std::endl;

// #include <mm.h>
#include <grass/iostream/mm.h>

#define MM_DEBUG if (0)

/* ************************************************************ */
MM_register::MM_register()
{

    instances++;
    if (instances > 1) {
        cerr << "MM_register(): Only 1 instance of MM_register should exist.\n";
        assert(0); // core dump if debugging
        exit(1);
    }
    assert(instances == 1);

    // by default, we ignore if memory limit is exceeded
    register_new = MM_IGNORE_MEMORY_EXCEEDED;
}

/* ************************************************************ */
MM_register::~MM_register(void)
{

    if (instances > 1) {
        cerr << "MM_register(): Only 1 instance of MM_register should exist.\n";
        assert(0); // core dump if debugging
        exit(1);
    }
    assert(instances == 1);
    instances--;
}

/* ************************************************************ */
void MM_register::print()
{

    size_t availMB = (remaining >> 20);
    if (remaining) {
        cout << "available memory: " << availMB << "MB "
             << "(" << remaining << "B)" << endl;
    }
    else {
        cout << "available memory: " << remaining
             << "B, exceeding: " << used - user_limit << "B" << endl;
    }
}

/* ************************************************************ */
// User-callable method to set allowable memory size
MM_err MM_register::set_memory_limit(size_t new_limit)
{

    assert(new_limit > 0);
    if (used > new_limit) {
        //    return MM_ERROR_EXCESSIVE_ALLOCATION;
        switch (register_new) {
        case MM_ABORT_ON_MEMORY_EXCEEDED:
            cerr << " MM_register::set_memory_limit to " << new_limit
                 << ", used " << used << ". allocation exceeds new limit.\n";
            cerr.flush();
            assert(0); // core dump if debugging
            exit(1);
            break;

        case MM_WARN_ON_MEMORY_EXCEEDED:
            cerr << " MM_register::set_memory_limit to " << new_limit
                 << ", used " << used << ". allocation exceeds new limit.\n";
            break;

        case MM_IGNORE_MEMORY_EXCEEDED:
            break;
        }
        user_limit = new_limit;
        remaining = 0;
        return MM_ERROR_NO_ERROR;
    }

    assert(used <= new_limit);
    // These are unsigned, so be careful.
    if (new_limit < user_limit) {
        remaining -= user_limit - new_limit;
    }
    else {
        remaining += new_limit - user_limit;
    }
    user_limit = new_limit;
    return MM_ERROR_NO_ERROR;
}

/* ************************************************************ */
// only warn if memory limit exceeded
void MM_register::warn_memory_limit()
{
    register_new = MM_WARN_ON_MEMORY_EXCEEDED;
}

/* ************************************************************ */
// abort if memory limit exceeded
void MM_register::enforce_memory_limit()
{
    register_new = MM_ABORT_ON_MEMORY_EXCEEDED;

    if (used > user_limit) {
        cerr << " MM_register::enforce_memory_limit: limit=" << user_limit
             << ", used=" << used << ". allocation exceeds limit.\n";
        assert(0); // core dump if debugging
        exit(1);
    }
}

/* ************************************************************ */
// ignore memory limit accounting
void MM_register::ignore_memory_limit()
{
    register_new = MM_IGNORE_MEMORY_EXCEEDED;
}

/* ************************************************************ */
// provide accounting state
MM_mode MM_register::get_limit_mode()
{
    return register_new;
}

/* ************************************************************ */
// provide print ccounting state
void MM_register::print_limit_mode()
{
    cout << "Memory manager registering memory in ";
    switch (register_new) {
    case MM_ABORT_ON_MEMORY_EXCEEDED:
        cout << "MM_ABORT_ON_MEMORY_EXCEEDED";
        break;
    case MM_WARN_ON_MEMORY_EXCEEDED:
        cout << "MM_WARN_ON_MEMORY_EXCEEDED";
        break;
    case MM_IGNORE_MEMORY_EXCEEDED:
        cout << "MM_IGNORE_MEMORY_EXCEEDED";
        break;
    }
    cout << " mode." << endl;
}

/* ************************************************************ */
// return the amount of memory available before user-specified memory
// limit will be exceeded
size_t MM_register::memory_available()
{
    return remaining;
}

/* ************************************************************ */
size_t MM_register::memory_used()
{
    return used;
}

/* ************************************************************ */
size_t MM_register::memory_limit()
{
    return user_limit;
}

/* ---------------------------------------------------------------------- */
// return the overhead on each memory allocation request

// SIZE_SPACE is to ensure alignment on quad word boundaries.  It may be
// possible to check whether a machine needs this at configuration
// time or if dword alignment is ok.  On the HP 9000, bus errors occur
// when loading doubles that are not qword aligned.
static const size_t SIZE_SPACE = (sizeof(size_t) > 8 ? sizeof(size_t) : 8);

int MM_register::space_overhead()
{
    return SIZE_SPACE;
}

/* ************************************************************ */
// check that new allocation request is below user-defined limit.
// This should be a private method, only called by operator new.
MM_err MM_register::register_allocation(size_t request)
{

    if (request > remaining) {
        remaining = 0;
        used += request;
        return MM_ERROR_INSUFFICIENT_SPACE;
    }
    else {
        used += request;
        remaining -= request;
        return MM_ERROR_NO_ERROR;
    }
}

/* ************************************************************ */
// do the accounting for a memory deallocation request.
// This should be a private method, only called by operators
// delete and delete [].
MM_err MM_register::register_deallocation(size_t sz)
{

    if (sz > used) {
        used = 0;
        remaining = user_limit;
        return MM_ERROR_UNDERFLOW;
    }
    else {

        used -= sz;
        if (used < user_limit) {
            remaining = user_limit - used;
        }
        else {
            assert(remaining == 0);
        }
        return MM_ERROR_NO_ERROR;
    }
}

/* ************************************************************ */
/* these overloaded operators must only be used by this memory manager
 * risk of invalid free if these operators are defined outside the MM_register
 * class e.g. GDAL allocating memory with something else than new as defined
 * here but then using delete as defined here
 */
#ifdef GRASS_MM_USE_EXCEPTION_SPECIFIER
void *MM_register::operator new[](size_t sz) throw(std::bad_alloc)
{
#else
void *MM_register::operator new[](size_t sz)
{
#endif /* GRASS_MM_USE_EXCEPTION_SPECIFIER */
    void *p;

    MM_DEBUG cout << "new: sz=" << sz << ", register " << sz + SIZE_SPACE
                  << "B ,";

    if (MM_manager.register_allocation(sz + SIZE_SPACE) != MM_ERROR_NO_ERROR) {
        // must be MM_ERROR_INSUF_SPACE
        switch (MM_manager.register_new) {

        case MM_ABORT_ON_MEMORY_EXCEEDED:
            cerr << "MM error: limit =" << MM_manager.memory_limit() << "B. "
                 << "allocating " << sz << "B. "
                 << "limit exceeded by "
                 << MM_manager.memory_used() - MM_manager.memory_limit() << "B."
                 << endl;
            assert(0); // core dump if debugging
            exit(1);
            break;

        case MM_WARN_ON_MEMORY_EXCEEDED:
            cerr << "MM warning: limit=" << MM_manager.memory_limit() << "B. "
                 << "allocating " << sz << "B. "
                 << " limit exceeded by "
                 << MM_manager.memory_used() - MM_manager.memory_limit() << "B."
                 << endl;
            break;

        case MM_IGNORE_MEMORY_EXCEEDED:
            break;
        }
    }

    p = malloc(sz + SIZE_SPACE);

    if (!p) {
        cerr << "new: out of memory while allocating " << sz << "B" << endl;
        assert(0);
        exit(1);
    }

    *((size_t *)p) = sz;

    MM_DEBUG cout << "ptr=" << (void *)(((char *)p) + SIZE_SPACE) << endl;

    return ((char *)p) + SIZE_SPACE;
}

/* ************************************************************ */
#ifdef GRASS_MM_USE_EXCEPTION_SPECIFIER
void *MM_register::operator new(size_t sz) throw(std::bad_alloc)
{
#else
void *MM_register::operator new(size_t sz)
{
#endif /* GRASS_MM_USE_EXCEPTION_SPECIFIER */
    void *p;

    MM_DEBUG cout << "new: sz=" << sz << ", register " << sz + SIZE_SPACE
                  << "B ,";

    if (MM_manager.register_allocation(sz + SIZE_SPACE) != MM_ERROR_NO_ERROR) {
        // must be MM_ERROR_INSUF_SPACE
        switch (MM_manager.register_new) {

        case MM_ABORT_ON_MEMORY_EXCEEDED:
            cerr << "MM error: limit =" << MM_manager.memory_limit() << "B. "
                 << "allocating " << sz << "B. "
                 << "limit exceeded by "
                 << MM_manager.memory_used() - MM_manager.memory_limit() << "B."
                 << endl;
            assert(0); // core dump if debugging
            exit(1);
            break;

        case MM_WARN_ON_MEMORY_EXCEEDED:
            cerr << "MM warning: limit=" << MM_manager.memory_limit() << "B. "
                 << "allocating " << sz << "B. "
                 << " limit exceeded by "
                 << MM_manager.memory_used() - MM_manager.memory_limit() << "B."
                 << endl;
            break;

        case MM_IGNORE_MEMORY_EXCEEDED:
            break;
        }
    }

    p = malloc(sz + SIZE_SPACE);

    if (!p) {
        cerr << "new: out of memory while allocating " << sz << "B" << endl;
        assert(0);
        exit(1);
    }

    *((size_t *)p) = sz;

    MM_DEBUG cout << "ptr=" << (void *)(((char *)p) + SIZE_SPACE) << endl;

    return ((char *)p) + SIZE_SPACE;
}

/* ---------------------------------------------------------------------- */
#ifdef GRASS_MM_USE_EXCEPTION_SPECIFIER
void MM_register::operator delete(void *ptr) throw()
{
#else
void MM_register::operator delete(void *ptr) noexcept
{
#endif /* GRASS_MM_USE_EXCEPTION_SPECIFIER */
    size_t sz;
    void *p;

    MM_DEBUG cout << "delete: ptr=" << ptr << ",";

    if (!ptr) {
        cerr << "MM warning: operator delete was given a NULL pointer\n";
        cerr.flush();
        // this may actually happen: for instance when calling a default
        // destructor for something that was not allocated with new
        // e.g. ofstream str(name) ---- ~ofstream() called ==> ptr=NULL

        // who wrote the above comment? -RW
        assert(0);
        // exit(1);
        return;
    }

    assert(ptr);

    /* causes invalid free if ptr has not been allocated with new as
     * defined above */
    p = ((char *)ptr) - SIZE_SPACE; // the base of memory
    sz = *((size_t *)p);

    MM_DEBUG cout << "size=" << sz << ", free " << p << "B and deallocate "
                  << sz + SIZE_SPACE << endl;

    if (MM_manager.register_deallocation(sz + SIZE_SPACE) !=
        MM_ERROR_NO_ERROR) {
        // must be MM_ERROR_UNDERFLOW
        cerr << "delete: MM_manager.register_deallocation failed\n";
        assert(0);
        exit(1);
    }

    free(p);
}

/* ---------------------------------------------------------------------- */
#ifdef GRASS_MM_USE_EXCEPTION_SPECIFIER
void MM_register::operator delete[](void *ptr) throw()
{
#else
void MM_register::operator delete[](void *ptr) noexcept
{
#endif /* GRASS_MM_USE_EXCEPTION_SPECIFIER */
    size_t sz;
    void *p;

    MM_DEBUG cout << "delete[]: ptr=" << ptr << ",";

    if (!ptr) {
        // can this happen? -- it does: see delete above
        cerr << "MM warning: operator delete [] was given a NULL pointer\n";
        cerr.flush();
        // assert(0);
        // exit(1);
        return;
    }
    assert(ptr);

    /* causes invalid free if ptr has not been allocated with new as
     * defined above */
    p = ((char *)ptr) - SIZE_SPACE; // the base of memory
    sz = *((size_t *)p);

    MM_DEBUG cout << "size=" << sz << ", free " << p << "B and deallocate "
                  << sz + SIZE_SPACE << endl;

    if (MM_manager.register_deallocation(sz + SIZE_SPACE) !=
        MM_ERROR_NO_ERROR) {
        // must be MM_ERROR_UNDERFLOW
        cerr << "delete[]: MM_manager.register_deallocation failed\n";
        assert(0);
        exit(1);
    }

    free(p);
}

/* ************************************************************ */
// Instantiate the actual memory manager, and allocate the
// its static data members
MM_register MM_manager;
int MM_register::instances = 0; // Number of instances. (init)
// TPIE's "register memory requests" flag
MM_mode MM_register::register_new = MM_IGNORE_MEMORY_EXCEEDED;
// This causes constructors for static variables to fail
// MM_mode MM_register::register_new = MM_ABORT_ON_MEMORY_EXCEEDED;

/* ************************************************************ */
// The counter of mm_register_init instances.  It is implicitly set to 0.
unsigned int mm_register_init::count;

// The constructor and destructor that ensure that the memory manager is
// created exactly once, and destroyed when appropriate.
mm_register_init::mm_register_init(void)
{
    if (count++ == 0) {
        MM_manager.set_memory_limit(MM_DEFAULT_MM_SIZE);
    }
}

mm_register_init::~mm_register_init(void)
{
    --count;
}