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author | Mike Hearn <hearn@google.com> | 2012-06-25 11:17:22 +0200 |
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committer | Pieter Wuille <pieter.wuille@gmail.com> | 2012-10-20 23:08:56 +0200 |
commit | 5e650d6d2dbfc284c300668e71188e663d8f0a45 (patch) | |
tree | bef5ac4e7bfa9845b23ea975be58fa3fe108ef4b /src/leveldb/port/port_example.h | |
parent | 38ac953b9df1f7a884c1ef0e94301e14c4e7477d (diff) | |
download | bitcoin-5e650d6d2dbfc284c300668e71188e663d8f0a45.tar.xz |
Import LevelDB 1.5, it will be used for the transaction database.
Diffstat (limited to 'src/leveldb/port/port_example.h')
-rw-r--r-- | src/leveldb/port/port_example.h | 135 |
1 files changed, 135 insertions, 0 deletions
diff --git a/src/leveldb/port/port_example.h b/src/leveldb/port/port_example.h new file mode 100644 index 0000000000..ab9e489b32 --- /dev/null +++ b/src/leveldb/port/port_example.h @@ -0,0 +1,135 @@ +// 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(); +}; + +// Thread-safe initialization. +// Used as follows: +// static port::OnceType init_control = LEVELDB_ONCE_INIT; +// static void Initializer() { ... do something ...; } +// ... +// port::InitOnce(&init_control, &Initializer); +typedef intptr_t OnceType; +#define LEVELDB_ONCE_INIT 0 +extern void InitOnce(port::OnceType*, void (*initializer)()); + +// 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); + +// If input[0,input_length-1] looks like a valid snappy compressed +// buffer, store the size of the uncompressed data in *result and +// return true. Else return false. +extern bool Snappy_GetUncompressedLength(const char* input, size_t length, + size_t* result); + +// Attempt to snappy uncompress input[0,input_length-1] into *output. +// Returns true if successful, false if the input is invalid lightweight +// compressed data. +// +// REQUIRES: at least the first "n" bytes of output[] must be writable +// where "n" is the result of a successful call to +// Snappy_GetUncompressedLength. +extern bool Snappy_Uncompress(const char* input_data, size_t input_length, + char* 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); + +} // namespace port +} // namespace leveldb + +#endif // STORAGE_LEVELDB_PORT_PORT_EXAMPLE_H_ |