SkContainers.h

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// Copyright 2022 Google LLC.
// Use of this source code is governed by a BSD-style license that can be found in the LICENSE file.
 
#ifndef SkContainers_DEFINED
#define SkContainers_DEFINED
 
#include "include/private/base/SkAPI.h"
#include "include/private/base/SkAlign.h"
#include "include/private/base/SkSpan_impl.h"
 
#include <cstddef>
#include <cstdint>
 
class SK_SPI SkContainerAllocator {
public:
    SkContainerAllocator(size_t sizeOfT, int maxCapacity)
            : fSizeOfT{sizeOfT}
            , fMaxCapacity{maxCapacity} {}
 
    // allocate will abort on failure. Given a capacity of 0, it will return the empty span.
    // The bytes allocated are freed using sk_free().
    SkSpan<std::byte> allocate(int capacity, double growthFactor = 1.0);
 
    // Rounds a requested capacity up towards `kCapacityMultiple` in a constexpr-friendly fashion.
    template <typename T>
    static constexpr size_t RoundUp(size_t capacity) {
        return SkAlignTo(capacity * sizeof(T), kCapacityMultiple) / sizeof(T);
    }
 
private:
    friend struct SkContainerAllocatorTestingPeer;
 
    // All capacity counts will be rounded up to kCapacityMultiple. This matches ASAN's shadow
    // granularity, as well as our typical struct alignment on a 64-bit machine.
    static constexpr int64_t kCapacityMultiple = 8;
 
    // Rounds up capacity to next multiple of kCapacityMultiple and pin to fMaxCapacity.
    size_t roundUpCapacity(int64_t capacity) const;
 
    // Grows the capacity by growthFactor being sure to stay with in kMinBytes and fMaxCapacity.
    size_t growthFactorCapacity(int capacity, double growthFactor) const;
 
    const size_t fSizeOfT;
    const int64_t fMaxCapacity;
};
 
// sk_allocate_canfail returns the empty span on failure. Parameter size must be > 0.
SkSpan<std::byte> sk_allocate_canfail(size_t size);
 
// Returns the empty span if size is 0. sk_allocate_throw aborts on failure.
SkSpan<std::byte> sk_allocate_throw(size_t size);
 
SK_SPI void sk_report_container_overflow_and_die();
#endif  // SkContainers_DEFINED