Você não pode selecionar mais de 25 tópicos
Os tópicos devem começar com uma letra ou um número, podem incluir traços ('-') e podem ter até 35 caracteres.
115 linhas
3.7 KiB
115 linhas
3.7 KiB
// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
|
|
// Use of this source code is governed by a BSD-style license that can be
|
|
// found in the LICENSE file. See the AUTHORS file for names of contributors.
|
|
//
|
|
// This file contains the specification, but not the implementations,
|
|
// of the types/operations/etc. that should be defined by a platform
|
|
// specific port_<platform>.h file. Use this file as a reference for
|
|
// how to port this package to a new platform.
|
|
|
|
#ifndef STORAGE_LEVELDB_PORT_PORT_EXAMPLE_H_
|
|
#define STORAGE_LEVELDB_PORT_PORT_EXAMPLE_H_
|
|
|
|
namespace leveldb {
|
|
namespace port {
|
|
|
|
// TODO(jorlow): Many of these belong more in the environment class rather than
|
|
// here. We should try moving them and see if it affects perf.
|
|
|
|
// The following boolean constant must be true on a little-endian machine
|
|
// and false otherwise.
|
|
static const bool kLittleEndian = true /* or some other expression */;
|
|
|
|
// ------------------ Threading -------------------
|
|
|
|
// A Mutex represents an exclusive lock.
|
|
class Mutex {
|
|
public:
|
|
Mutex();
|
|
~Mutex();
|
|
|
|
// Lock the mutex. Waits until other lockers have exited.
|
|
// Will deadlock if the mutex is already locked by this thread.
|
|
void Lock();
|
|
|
|
// Unlock the mutex.
|
|
// REQUIRES: This mutex was locked by this thread.
|
|
void Unlock();
|
|
|
|
// Optionally crash if this thread does not hold this mutex.
|
|
// The implementation must be fast, especially if NDEBUG is
|
|
// defined. The implementation is allowed to skip all checks.
|
|
void AssertHeld();
|
|
};
|
|
|
|
class CondVar {
|
|
public:
|
|
explicit CondVar(Mutex* mu);
|
|
~CondVar();
|
|
|
|
// Atomically release *mu and block on this condition variable until
|
|
// either a call to SignalAll(), or a call to Signal() that picks
|
|
// this thread to wakeup.
|
|
// REQUIRES: this thread holds *mu
|
|
void Wait();
|
|
|
|
// If there are some threads waiting, wake up at least one of them.
|
|
void Signal();
|
|
|
|
// Wake up all waiting threads.
|
|
void SignallAll();
|
|
};
|
|
|
|
// A type that holds a pointer that can be read or written atomically
|
|
// (i.e., without word-tearing.)
|
|
class AtomicPointer {
|
|
private:
|
|
intptr_t rep_;
|
|
public:
|
|
// Initialize to arbitrary value
|
|
AtomicPointer();
|
|
|
|
// Initialize to hold v
|
|
explicit AtomicPointer(void* v) : rep_(v) { }
|
|
|
|
// Read and return the stored pointer with the guarantee that no
|
|
// later memory access (read or write) by this thread can be
|
|
// reordered ahead of this read.
|
|
void* Acquire_Load() const;
|
|
|
|
// Set v as the stored pointer with the guarantee that no earlier
|
|
// memory access (read or write) by this thread can be reordered
|
|
// after this store.
|
|
void Release_Store(void* v);
|
|
|
|
// Read the stored pointer with no ordering guarantees.
|
|
void* NoBarrier_Load() const;
|
|
|
|
// Set va as the stored pointer with no ordering guarantees.
|
|
void NoBarrier_Store(void* v);
|
|
};
|
|
|
|
// ------------------ Compression -------------------
|
|
|
|
// Store the snappy compression of "input[0,input_length-1]" in *output.
|
|
// Returns false if snappy is not supported by this port.
|
|
extern bool Snappy_Compress(const char* input, size_t input_length,
|
|
std::string* output);
|
|
|
|
// Attempt to snappy uncompress input[0,input_length-1] into *output.
|
|
// Returns true if successful, false if the input is invalid lightweight
|
|
// compressed data.
|
|
extern bool Snappy_Uncompress(const char* input_data, size_t input_length,
|
|
std::string* output);
|
|
|
|
// ------------------ Miscellaneous -------------------
|
|
|
|
// If heap profiling is not supported, returns false.
|
|
// Else repeatedly calls (*func)(arg, data, n) and then returns true.
|
|
// The concatenation of all "data[0,n-1]" fragments is the heap profile.
|
|
extern bool GetHeapProfile(void (*func)(void*, const char*, int), void* arg);
|
|
|
|
}
|
|
}
|
|
|
|
#endif // STORAGE_LEVELDB_PORT_PORT_EXAMPLE_H_
|