Move shared files in net/quic/ into net/quic/core/

net/quic/iovector.h

-// Copyright 2013 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#ifndef NET_QUIC_IOVECTOR_H_
-#define NET_QUIC_IOVECTOR_H_
-
-#include <stddef.h>
-
-#include <algorithm>
-#include <vector>
-
-#include "base/logging.h"
-#include "net/base/iovec.h"
-#include "net/base/net_export.h"
-
-namespace net {
-
-// Calculate the total number of bytes in an array of iovec structures.
-inline size_t TotalIovecLength(const struct iovec* iov, size_t iovcnt) {
-  size_t length = 0;
-  if (iov != NULL) {
-    for (size_t i = 0; i < iovcnt; ++i) {
-      length += iov[i].iov_len;
-    }
-  }
-  return length;
-}
-
-// IOVector is a helper class that makes it easier to work with POSIX vector I/O
-// struct. It is a thin wrapper by design and thus has no virtual functions and
-// all inlined methods. This class makes no assumptions about the ordering of
-// the pointer values of the blocks appended, it simply counts bytes when asked
-// to consume bytes.
-//
-// IOVector is a bookkeeping object that collects a description of buffers to
-// be read or written together and in order. It does not take ownership of the
-// blocks appended.
-//
-// Because it is used for scatter-gather operations, the order in which the
-// buffer blocks are added to the IOVector is important to the client. The
-// intended usage pattern is:
-//
-//   iovector.Append(p0, len0);
-//   ...
-//   iovector.Append(pn, lenn);
-//   int bytes_written = writev(fd, iovector.iovec(), iovector.Size());
-//   if (bytes_written > 0)
-//     iovector.Consume(bytes_written);
-//
-// The sequence is the same for readv, except that Consume() in this case is
-// used to change the IOVector to only keep track of description of blocks of
-// memory not yet written to.
-//
-// IOVector does not have any method to change the iovec entries that it
-// accumulates. This is due to the block merging nature of Append(): we'd like
-// to avoid accidentally change an entry that is assembled by two or more
-// Append()'s by simply an index access.
-//
-class NET_EXPORT_PRIVATE IOVector {
- public:
-  // Provide a default constructor so it'll never be inhibited by adding other
-  // constructors.
-  IOVector();
-  IOVector(const IOVector& other);
-  ~IOVector();
-
-  // Provides a way to convert system call-like iovec representation to
-  // IOVector.
-  void AppendIovec(const struct iovec* iov, size_t iovcnt) {
-    for (size_t i = 0; i < iovcnt; ++i)
-      Append(static_cast<char*>(iov[i].iov_base), iov[i].iov_len);
-  }
-
-  // Appends at most max_bytes from iovec to the IOVector.
-  size_t AppendIovecAtMostBytes(const struct iovec* iov,
-                                size_t iovcnt,
-                                size_t max_bytes) {
-    size_t bytes_appended = 0;
-    for (size_t i = 0; i < iovcnt && max_bytes > 0; ++i) {
-      const size_t length = std::min(max_bytes, iov[i].iov_len);
-      Append(static_cast<char*>(iov[i].iov_base), length);
-      max_bytes -= length;
-      bytes_appended += length;
-    }
-    return bytes_appended;
-  }
-
-  // Append another block to the IOVector. Since IOVector can be used for read
-  // and write, it always takes char*. Clients that writes will need to cast
-  // away the constant of the pointer before appending a block.
-  void Append(char* buffer, size_t length) {
-    if (buffer != nullptr && length > 0) {
-      if (iovec_.size() > 0) {
-        struct iovec& last = iovec_.back();
-        // If the new block is contiguous with the last block, just extend.
-        if (static_cast<char*>(last.iov_base) + last.iov_len == buffer) {
-          last.iov_len += length;
-          return;
-        }
-      }
-      struct iovec tmp = {buffer, length};
-      iovec_.push_back(tmp);
-    }
-  }
-
-  // Same as Append, but doesn't do the tail merge optimization.
-  // Intended for testing.
-  void AppendNoCoalesce(char* buffer, size_t length) {
-    if (buffer != nullptr && length > 0) {
-      struct iovec tmp = {buffer, length};
-      iovec_.push_back(tmp);
-    }
-  }
-
-  // Remove a number of bytes from the beginning of the IOVector. Since vector
-  // I/O operations always occur at the beginning of the block list, a method
-  // to remove bytes at the end is not provided.
-  // It returns the number of bytes actually consumed (it'll only be smaller
-  // than the requested number if the IOVector contains less data).
-  size_t Consume(size_t length) {
-    if (length == 0)
-      return 0;
-
-    size_t bytes_to_consume = length;
-    std::vector<struct iovec>::iterator iter = iovec_.begin();
-    std::vector<struct iovec>::iterator end = iovec_.end();
-    for (; iter < end && bytes_to_consume >= iter->iov_len; ++iter) {
-      bytes_to_consume -= iter->iov_len;
-    }
-    iovec_.erase(iovec_.begin(), iter);
-    if (!iovec_.empty() && bytes_to_consume != 0) {
-      iovec_[0].iov_base =
-          static_cast<char*>(iovec_[0].iov_base) + bytes_to_consume;
-      iovec_[0].iov_len -= bytes_to_consume;
-      return length;
-    }
-    if (iovec_.size() == 0 && bytes_to_consume > 0) {
-      LOG(DFATAL) << "Attempting to consume " << bytes_to_consume
-                  << " non-existent bytes.";
-    }
-    // At this point bytes_to_consume is the number of wanted bytes left over
-    // after walking through all the iovec entries.
-    return length - bytes_to_consume;
-  }
-
-  // Identical to Consume, but also copies the portion of the buffer being
-  // consumed into |buffer|.  |buffer| must be at least size |length|.  If
-  // the IOVector is less than |length|, the method consumes the entire
-  // IOVector, logs an error and returns the length consumed.
-  size_t ConsumeAndCopy(size_t length, char* buffer) {
-    if (length == 0)
-      return 0;
-
-    size_t bytes_to_consume = length;
-    // First consume all the iovecs which can be consumed completely.
-    std::vector<struct iovec>::iterator iter = iovec_.begin();
-    std::vector<struct iovec>::iterator end = iovec_.end();
-    for (; iter < end && bytes_to_consume >= iter->iov_len; ++iter) {
-      memcpy(buffer, iter->iov_base, iter->iov_len);
-      bytes_to_consume -= iter->iov_len;
-      buffer += iter->iov_len;
-    }
-    iovec_.erase(iovec_.begin(), iter);
-    if (bytes_to_consume == 0) {
-      return length;
-    }
-    if (iovec_.empty()) {
-      LOG_IF(DFATAL, bytes_to_consume > 0) << "Attempting to consume "
-                                           << bytes_to_consume
-                                           << " non-existent bytes.";
-      return length - bytes_to_consume;
-    }
-    // Partially consume the next iovec.
-    memcpy(buffer, iovec_[0].iov_base, bytes_to_consume);
-    iovec_[0].iov_base =
-        static_cast<char*>(iovec_[0].iov_base) + bytes_to_consume;
-    iovec_[0].iov_len -= bytes_to_consume;
-    return length;
-  }
-
-  // TODO(joechan): If capacity is large, swap out for a blank one.
-  // Clears the IOVector object to contain no blocks.
-  void Clear() { iovec_.clear(); }
-
-  // Swap the guts of two IOVector.
-  void Swap(IOVector* other) { iovec_.swap(other->iovec_); }
-
-  // Returns the number of valid blocks in the IOVector (not the number of
-  // bytes).
-  size_t Size() const { return iovec_.size(); }
-
-  // Returns the total storage used by the IOVector in number of blocks (not
-  // the number of bytes).
-  size_t Capacity() const { return iovec_.capacity(); }
-
-  // Returns true if there are no blocks in the IOVector.
-  bool Empty() const { return iovec_.empty(); }
-
-  // Returns the pointer to the beginning of the iovec to be used for vector
-  // I/O operations. If the IOVector has no blocks appened, this function
-  // returns NULL.
-  struct iovec* iovec() {
-    return !Empty() ? &iovec_[0] : NULL;
-  }
-
-  // Const version.
-  const struct iovec* iovec() const { return !Empty() ? &iovec_[0] : NULL; }
-
-  // Returns a pointer to one past the last byte of the last block. If the
-  // IOVector is empty, NULL is returned.
-  const char* LastBlockEnd() const {
-    return iovec_.size() > 0
-               ? static_cast<char*>(iovec_.back().iov_base) +
-                     iovec_.back().iov_len
-               : NULL;
-  }
-
-  // Returns the total number of bytes in the IOVector.
-  size_t TotalBufferSize() const { return TotalIovecLength(iovec(), Size()); }
-
-  void Resize(size_t count) { iovec_.resize(count); }
-
- private:
-  std::vector<struct iovec> iovec_;
-
-  // IOVector has value-semantics; copy and assignment are allowed.
-  // This class does not explicitly define copy/move constructors or the
-  // assignment operator to preserve compiler-generated copy/move constructors
-  // and assignment operators. Note that since IOVector does not own the
-  // actual buffers that the struct iovecs point to, copies and assignments
-  // result in a shallow copy of the buffers; resulting IOVectors will point
-  // to the same copy of the underlying data.
-};
-
-}  // namespace net
-
-#endif  // NET_QUIC_IOVECTOR_H_