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/* Like std::ofstream but without being incredibly slow. Backed by a raw fd.
* Supports most of the built-in types except for void* and long double.
*/
#ifndef UTIL_FAKE_OFSTREAM_H
#define UTIL_FAKE_OFSTREAM_H
#include "util/file.hh"
#include "util/float_to_string.hh"
#include "util/integer_to_string.hh"
#include "util/scoped.hh"
#include "util/string_piece.hh"
#include <cassert>
#include <cstring>
#include <stdint.h>
namespace util {
class FakeOFStream {
public:
// Maximum over all ToString operations.
// static const std::size_t kMinBuf = 20;
// This was causing compile failures in debug, so now 20 is written directly.
//
// Does not take ownership of out.
// Allows default constructor, but must call SetFD.
explicit FakeOFStream(int out = -1, std::size_t buffer_size = 1048576)
: buf_(util::MallocOrThrow(std::max(buffer_size, (size_t)20))),
current_(static_cast<char*>(buf_.get())),
end_(current_ + std::max(buffer_size, (size_t)20)),
fd_(out) {}
~FakeOFStream() {
// Could have called Finish already
flush();
}
void SetFD(int to) {
flush();
fd_ = to;
}
FakeOFStream &write(const void *data, std::size_t length) {
if (UTIL_LIKELY(current_ + length <= end_)) {
std::memcpy(current_, data, length);
current_ += length;
return *this;
}
flush();
if (current_ + length <= end_) {
std::memcpy(current_, data, length);
current_ += length;
} else {
util::WriteOrThrow(fd_, data, length);
}
return *this;
}
// This also covers std::string and char*
FakeOFStream &operator<<(StringPiece str) {
return write(str.data(), str.size());
}
// For anything with ToStringBuf<T>::kBytes, define operator<< using ToString.
// This includes uint64_t, int64_t, uint32_t, int32_t, uint16_t, int16_t,
// float, double
private:
template <int Arg> struct EnableIfKludge {
typedef FakeOFStream type;
};
public:
template <class T> typename EnableIfKludge<ToStringBuf<T>::kBytes>::type &operator<<(const T value) {
EnsureRemaining(ToStringBuf<T>::kBytes);
current_ = ToString(value, current_);
assert(current_ <= end_);
return *this;
}
FakeOFStream &operator<<(char c) {
EnsureRemaining(1);
*current_++ = c;
return *this;
}
FakeOFStream &operator<<(unsigned char c) {
EnsureRemaining(1);
*current_++ = static_cast<char>(c);
return *this;
}
/* clang on OS X appears to consider std::size_t aka unsigned long distinct
* from uint64_t. So this function makes clang work. gcc considers
* uint64_t and std::size_t the same (on 64-bit) so this isn't necessary.
* But it does no harm since gcc sees it as a specialization of the
* EnableIfKludge template.
* Also, delegating to *this << static_cast<uint64_t>(value) would loop
* indefinitely on gcc.
*/
FakeOFStream &operator<<(std::size_t value) {
EnsureRemaining(ToStringBuf<uint64_t>::kBytes);
current_ = ToString(static_cast<uint64_t>(value), current_);
return *this;
}
// Note this does not sync.
void flush() {
if (current_ != buf_.get()) {
util::WriteOrThrow(fd_, buf_.get(), current_ - (char*)buf_.get());
current_ = static_cast<char*>(buf_.get());
}
}
// Not necessary, but does assure the data is cleared.
void Finish() {
flush();
buf_.reset();
current_ = NULL;
util::FSyncOrThrow(fd_);
}
private:
void EnsureRemaining(std::size_t amount) {
if (UTIL_UNLIKELY(current_ + amount > end_)) {
flush();
assert(current_ + amount <= end_);
}
}
util::scoped_malloc buf_;
char *current_, *end_;
int fd_;
};
} // namespace
#endif
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