/*
- * Copyright 2016 Facebook, Inc.
+ * Copyright 2017 Facebook, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
#include <memory>
#include <folly/Bits.h>
-#include <folly/io/IOBuf.h>
-#include <folly/io/IOBufQueue.h>
#include <folly/Likely.h>
#include <folly/Memory.h>
#include <folly/Portability.h>
#include <folly/Range.h>
+#include <folly/io/IOBuf.h>
+#include <folly/io/IOBufQueue.h>
+#include <folly/portability/BitsFunctexcept.h>
/**
* Cursor class for fast iteration over IOBuf chains.
/**
* Return the remaining space available in the current IOBuf.
*
- * May return 0 if the cursor is at the end of an IOBuf. Use peek() instead
- * if you want to avoid this. peek() will advance to the next non-empty
- * IOBuf (up to the end of the chain) if the cursor is currently pointing at
- * the end of a buffer.
+ * May return 0 if the cursor is at the end of an IOBuf. Use peekBytes()
+ * instead if you want to avoid this. peekBytes() will advance to the next
+ * non-empty IOBuf (up to the end of the chain) if the cursor is currently
+ * pointing at the end of a buffer.
*/
size_t length() const {
return crtBuf_->length() - offset_;
return true;
}
+ /**
+ * Advances the cursor to the end of the entire IOBuf chain.
+ */
+ void advanceToEnd() {
+ offset_ = buffer_->prev()->length();
+ if (crtBuf_ != buffer_->prev()) {
+ crtBuf_ = buffer_->prev();
+ static_cast<Derived*>(this)->advanceDone();
+ }
+ }
+
Derived& operator+=(size_t offset) {
Derived* p = static_cast<Derived*>(this);
p->skip(offset);
return other;
}
+ Derived& operator-=(size_t offset) {
+ Derived* p = static_cast<Derived*>(this);
+ p->retreat(offset);
+ return *p;
+ }
+ Derived operator-(size_t offset) const {
+ Derived other(*this);
+ other.retreat(offset);
+ return other;
+ }
+
/**
* Compare cursors for equality/inequality.
*
}
template <class T>
- typename std::enable_if<std::is_arithmetic<T>::value, T>::type read() {
- T val;
+ typename std::enable_if<std::is_arithmetic<T>::value, bool>::type tryRead(
+ T& val) {
if (LIKELY(length() >= sizeof(T))) {
val = loadUnaligned<T>(data());
offset_ += sizeof(T);
advanceBufferIfEmpty();
- } else {
- pullSlow(&val, sizeof(T));
+ return true;
+ }
+ return pullAtMostSlow(&val, sizeof(T)) == sizeof(T);
+ }
+
+ template <class T>
+ bool tryReadBE(T& val) {
+ const bool result = tryRead(val);
+ val = Endian::big(val);
+ return result;
+ }
+
+ template <class T>
+ bool tryReadLE(T& val) {
+ const bool result = tryRead(val);
+ val = Endian::little(val);
+ return result;
+ }
+
+ template <class T>
+ T read() {
+ T val{};
+ if (!tryRead(val)) {
+ std::__throw_out_of_range("underflow");
}
return val;
}
*/
std::string readTerminatedString(
char termChar = '\0',
- size_t maxLength = std::numeric_limits<size_t>::max()) {
- std::string str;
-
- while (!isAtEnd()) {
- const uint8_t* buf = data();
- size_t buflen = length();
-
- size_t i = 0;
- while (i < buflen && buf[i] != termChar) {
- ++i;
+ size_t maxLength = std::numeric_limits<size_t>::max());
- // Do this check after incrementing 'i', as even though we start at the
- // 0 byte, it still represents a single character
- if (str.length() + i >= maxLength) {
- throw std::length_error("string overflow");
- }
- }
+ /*
+ * Read all bytes until the specified predicate returns true.
+ *
+ * The predicate will be called on each byte in turn, until it returns false
+ * or until the end of the IOBuf chain is reached.
+ *
+ * Returns the result as a string.
+ */
+ template <typename Predicate>
+ std::string readWhile(const Predicate& predicate);
- str.append(reinterpret_cast<const char*>(buf), i);
- if (i < buflen) {
- skip(i + 1);
- return str;
- }
+ /*
+ * Read all bytes until the specified predicate returns true.
+ *
+ * This is a more generic version of readWhile() takes an arbitrary Output
+ * object, and calls Output::append() with each chunk of matching data.
+ */
+ template <typename Predicate, typename Output>
+ void readWhile(const Predicate& predicate, Output& out);
- skip(i);
- }
- throw std::out_of_range("terminator not found");
- }
+ /*
+ * Skip all bytes until the specified predicate returns true.
+ *
+ * The predicate will be called on each byte in turn, until it returns false
+ * or until the end of the IOBuf chain is reached.
+ */
+ template <typename Predicate>
+ void skipWhile(const Predicate& predicate);
size_t skipAtMost(size_t len) {
if (LIKELY(length() >= len)) {
}
}
+ size_t retreatAtMost(size_t len) {
+ if (len <= offset_) {
+ offset_ -= len;
+ return len;
+ }
+ return retreatAtMostSlow(len);
+ }
+
+ void retreat(size_t len) {
+ if (len <= offset_) {
+ offset_ -= len;
+ } else {
+ retreatSlow(len);
+ }
+ }
+
size_t pullAtMost(void* buf, size_t len) {
// Fast path: it all fits in one buffer.
if (LIKELY(length() >= len)) {
/**
* Return the available data in the current buffer.
* If you want to gather more data from the chain into a contiguous region
- * (for hopefully zero-copy access), use gather() before peek().
+ * (for hopefully zero-copy access), use gather() before peekBytes().
*/
- std::pair<const uint8_t*, size_t> peek() {
+ ByteRange peekBytes() {
// Ensure that we're pointing to valid data
size_t available = length();
while (UNLIKELY(available == 0 && tryAdvanceBuffer())) {
available = length();
}
- return std::make_pair(data(), available);
+ return ByteRange{data(), available};
+ }
+
+ /**
+ * Alternate version of peekBytes() that returns a std::pair
+ * instead of a ByteRange. (This method pre-dates ByteRange.)
+ *
+ * This function will eventually be deprecated.
+ */
+ std::pair<const uint8_t*, size_t> peek() {
+ auto bytes = peekBytes();
+ return std::make_pair(bytes.data(), bytes.size());
}
void clone(std::unique_ptr<folly::IOBuf>& buf, size_t len) {
if (UNLIKELY(cloneAtMost(buf, len) != len)) {
- throw std::out_of_range("underflow");
+ std::__throw_out_of_range("underflow");
}
}
void clone(folly::IOBuf& buf, size_t len) {
if (UNLIKELY(cloneAtMost(buf, len) != len)) {
- throw std::out_of_range("underflow");
+ std::__throw_out_of_range("underflow");
}
}
size_t cloneAtMost(std::unique_ptr<folly::IOBuf>& buf, size_t len) {
if (!buf) {
- buf = make_unique<folly::IOBuf>();
+ buf = std::make_unique<folly::IOBuf>();
}
return cloneAtMost(*buf, len);
}
}
if (otherBuf == other.buffer_) {
- throw std::out_of_range("wrap-around");
+ std::__throw_out_of_range("wrap-around");
}
len += offset_;
} else {
if (offset_ < other.offset_) {
- throw std::out_of_range("underflow");
+ std::__throw_out_of_range("underflow");
}
len += offset_ - other.offset_;
size_t operator-(const BufType* buf) const {
size_t len = 0;
- BufType *curBuf = buf;
+ const BufType* curBuf = buf;
while (curBuf != crtBuf_) {
len += curBuf->length();
curBuf = curBuf->next();
if (curBuf == buf || curBuf == buffer_) {
- throw std::out_of_range("wrap-around");
+ std::__throw_out_of_range("wrap-around");
}
}
return true;
}
+ bool tryRetreatBuffer() {
+ if (UNLIKELY(crtBuf_ == buffer_)) {
+ offset_ = 0;
+ return false;
+ }
+ crtBuf_ = crtBuf_->prev();
+ offset_ = crtBuf_->length();
+ static_cast<Derived*>(this)->advanceDone();
+ return true;
+ }
+
void advanceBufferIfEmpty() {
if (length() == 0) {
tryAdvanceBuffer();
for (size_t available; (available = length()) < len; ) {
str->append(reinterpret_cast<const char*>(data()), available);
if (UNLIKELY(!tryAdvanceBuffer())) {
- throw std::out_of_range("string underflow");
+ std::__throw_out_of_range("string underflow");
}
len -= available;
}
void pullSlow(void* buf, size_t len) {
if (UNLIKELY(pullAtMostSlow(buf, len) != len)) {
- throw std::out_of_range("underflow");
+ std::__throw_out_of_range("underflow");
}
}
void skipSlow(size_t len) {
if (UNLIKELY(skipAtMostSlow(len) != len)) {
- throw std::out_of_range("underflow");
+ std::__throw_out_of_range("underflow");
+ }
+ }
+
+ size_t retreatAtMostSlow(size_t len) {
+ size_t retreated = 0;
+ for (size_t available; (available = offset_) < len;) {
+ retreated += available;
+ if (UNLIKELY(!tryRetreatBuffer())) {
+ return retreated;
+ }
+ len -= available;
+ }
+ offset_ -= len;
+ return retreated + len;
+ }
+
+ void retreatSlow(size_t len) {
+ if (UNLIKELY(retreatAtMostSlow(len) != len)) {
+ std::__throw_out_of_range("underflow");
}
}
void push(const uint8_t* buf, size_t len) {
Derived* d = static_cast<Derived*>(this);
if (d->pushAtMost(buf, len) != len) {
- throw std::out_of_range("overflow");
+ std::__throw_out_of_range("overflow");
}
}
void push(ByteRange buf) {
if (this->pushAtMost(buf) != buf.size()) {
- throw std::out_of_range("overflow");
+ std::__throw_out_of_range("overflow");
}
}
*/
void push(Cursor cursor, size_t len) {
if (this->pushAtMost(cursor, len) != len) {
- throw std::out_of_range("overflow");
+ std::__throw_out_of_range("overflow");
}
}
size_t pushAtMost(Cursor cursor, size_t len) {
size_t written = 0;
for(;;) {
- auto currentBuffer = cursor.peek();
- const uint8_t* crtData = currentBuffer.first;
- size_t available = currentBuffer.second;
+ auto currentBuffer = cursor.peekBytes();
+ const uint8_t* crtData = currentBuffer.data();
+ size_t available = currentBuffer.size();
if (available == 0) {
// end of buffer chain
return written;
using detail::Writable<RWCursor<access>>::pushAtMost;
size_t pushAtMost(const uint8_t* buf, size_t len) {
+ // We have to explicitly check for an input length of 0.
+ // We support buf being nullptr in this case, but we need to avoid calling
+ // memcpy() with a null source pointer, since that is undefined behavior
+ // even if the length is 0.
+ if (len == 0) {
+ return 0;
+ }
+
size_t copied = 0;
for (;;) {
// Fast path: the current buffer is big enough.
// Waste the rest of the current buffer and allocate a new one.
// Don't make it too small, either.
if (growth_ == 0) {
- throw std::out_of_range("can't grow buffer chain");
+ std::__throw_out_of_range("can't grow buffer chain");
}
n = std::max(n, growth_);
using detail::Writable<Appender>::pushAtMost;
size_t pushAtMost(const uint8_t* buf, size_t len) {
+ // We have to explicitly check for an input length of 0.
+ // We support buf being nullptr in this case, but we need to avoid calling
+ // memcpy() with a null source pointer, since that is undefined behavior
+ // even if the length is 0.
+ if (len == 0) {
+ return 0;
+ }
+
size_t copied = 0;
for (;;) {
// Fast path: it all fits in one buffer.
using detail::Writable<QueueAppender>::pushAtMost;
size_t pushAtMost(const uint8_t* buf, size_t len) {
- size_t remaining = len;
+ // Fill the current buffer
+ const size_t copyLength = std::min(len, length());
+ if (copyLength != 0) {
+ memcpy(writableData(), buf, copyLength);
+ append(copyLength);
+ buf += copyLength;
+ }
+ // Allocate more buffers as necessary
+ size_t remaining = len - copyLength;
while (remaining != 0) {
auto p = queue_->preallocate(std::min(remaining, growth_),
growth_,
};
}} // folly::io
+
+#include <folly/io/Cursor-inl.h>
projects / folly.git / blobdiff