Source/bmalloc/libpas/src/libpas/pas_try_allocate.h

/*
 * Copyright (c) 2018-2021 Apple Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
 */

#ifndef PAS_TRY_ALLOCATE_H
#define PAS_TRY_ALLOCATE_H

#include "pas_allocator_counts.h"
#include "pas_cares_about_size_mode.h"
#include "pas_heap.h"
#include "pas_heap_config.h"
#include "pas_heap_ref.h"
#include "pas_local_allocator_inlines.h"
#include "pas_physical_memory_transaction.h"
#include "pas_segregated_heap.h"
#include "pas_thread_local_cache.h"
#include "pas_try_allocate_common.h"
#include "pas_typed_allocation_result.h"

PAS_BEGIN_EXTERN_C;

/* This is for heaps that hold typed objects. These objects have a certain size. We may allocate
   arrays of these objects, but the entrypoints in this header are for the case where we are allocating
   just a single instance. We my allocate these objects with any alignment, but the entrypoints in this
   header are for the case where we are allocating with the alignment that was specified in the
   heap_ref's type.

   If you want to allocate with nontrivial count (i.e. an array) or nontrivial alignment (i.e. memalign)
   then use the pas_try_allocate_array.h entrypoints. */

typedef struct {
    pas_heap_ref* heap_ref;
    pas_heap_config config;
} pas_try_allocate_impl_size_thunk_data;

static PAS_ALWAYS_INLINE size_t pas_try_allocate_impl_size_thunk(void* arg)
{
    pas_try_allocate_impl_size_thunk_data* data;

    data = (pas_try_allocate_impl_size_thunk_data*)arg;

    return data->config.get_type_size(data->heap_ref->type);
}

static PAS_ALWAYS_INLINE pas_typed_allocation_result
pas_try_allocate_impl(pas_heap_ref* heap_ref,
                      pas_heap_config config,
                      pas_try_allocate_common_fast try_allocate_common_fast,
                      pas_try_allocate_common_slow try_allocate_common_slow)
{
    static const bool verbose = false;
    
    pas_heap_type* type;
    size_t type_size;
    pas_local_allocator_result allocator;
    unsigned allocator_index;
    pas_thread_local_cache* cache;
    pas_typed_allocation_result result;

    allocator_index = heap_ref->allocator_index;
    cache = pas_thread_local_cache_try_get();
    if (PAS_LIKELY(cache)) {
        allocator = pas_thread_local_cache_try_get_local_allocator(
            cache,
            allocator_index);

        if (verbose)
            pas_log("Got an allocator.\n");
        
        if (PAS_LIKELY(allocator.did_succeed)) {
            pas_allocation_result result;
            pas_try_allocate_impl_size_thunk_data size_thunk_data;
            
            /* This thing with the size thunk means that isoheaps usually don't have to get the
               heap's type or size, unless we are in a heap config that uses the .type or .size
               properties of typed allocation results. */
            size_thunk_data.config = config;
            size_thunk_data.heap_ref = heap_ref;

            result = try_allocate_common_fast(
                (pas_local_allocator*)allocator.allocator, pas_try_allocate_impl_size_thunk,
                &size_thunk_data, 1);

            type = heap_ref->type;
            return pas_typed_allocation_result_create_with_intrinsic_allocation_result(
                result, type, config.get_type_size(type));
        }

        if (verbose)
            pas_log("Did not succeed at getting an allocator.\n");
    }

    type = heap_ref->type;
    type_size = config.get_type_size(type);

    if (verbose)
        pas_log("Allocating the slow way.\n");

    result = pas_typed_allocation_result_create_with_intrinsic_allocation_result(
        try_allocate_common_slow(heap_ref, 1, type_size, 1),
        type, type_size);

    if (verbose)
        pas_log("result.ptr = %p, result.did_succeed = %d\n", result.ptr, result.did_succeed);

    return result;
}

#define PAS_CREATE_TRY_ALLOCATE(name, heap_config, runtime_config, allocator_counts, result_filter) \
    PAS_CREATE_TRY_ALLOCATE_COMMON( \
        name ## _impl, \
        pas_normal_heap_ref_kind, \
        (heap_config), \
        (runtime_config), \
        (allocator_counts), \
        pas_avoid_count_lookup, \
        (result_filter)); \
    \
    static PAS_ALWAYS_INLINE pas_typed_allocation_result name(pas_heap_ref* heap_ref) \
    { \
        return pas_try_allocate_impl( \
            heap_ref, (heap_config), name ## _impl_fast, name ## _impl_slow); \
    } \
    \
    static PAS_UNUSED PAS_NEVER_INLINE pas_typed_allocation_result \
    name ## _for_realloc(pas_heap_ref* heap_ref) \
    { \
        return name(heap_ref); \
    } \
    \
    struct pas_dummy

typedef pas_typed_allocation_result (*pas_try_allocate)(pas_heap_ref* heap_ref);

PAS_END_EXTERN_C;

#endif /* PAS_TRY_ALLOCATE_H */