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| 1 // Copyright 2014 The Chromium Authors. All rights reserved. |
| 2 // Use of this source code is governed by a BSD-style license that can be |
| 3 // found in the LICENSE file. |
| 4 |
| 5 #include "mojo/embedder/platform_channel_utils_posix.h" |
| 6 |
| 7 #include <sys/socket.h> |
| 8 #include <sys/uio.h> |
| 9 #include <unistd.h> |
| 10 |
| 11 #include "base/posix/eintr_wrapper.h" |
| 12 #include "build/build_config.h" |
| 13 |
| 14 namespace mojo { |
| 15 namespace embedder { |
| 16 |
| 17 // On Linux, |SIGPIPE| is suppressed by passing |MSG_NOSIGNAL| to |
| 18 // |send()|/|sendmsg()|. (There is no way of suppressing |SIGPIPE| on |
| 19 // |write()|/|writev().) On Mac, |SIGPIPE| is suppressed by setting the |
| 20 // |SO_NOSIGPIPE| option on the socket. |
| 21 // |
| 22 // Performance notes: |
| 23 // - On Linux, we have to use |send()|/|sendmsg()| rather than |
| 24 // |write()|/|writev()| in order to suppress |SIGPIPE|. This is okay, since |
| 25 // |send()| is (slightly) faster than |write()| (!), while |sendmsg()| is |
| 26 // quite comparable to |writev()|. |
| 27 // - On Mac, we may use |write()|/|writev()|. Here, |write()| is considerably |
| 28 // faster than |send()|, whereas |sendmsg()| is quite comparable to |
| 29 // |writev()|. |
| 30 // - On both platforms, an appropriate |sendmsg()|/|writev()| is considerably |
| 31 // faster than two |send()|s/|write()|s. |
| 32 // - Relative numbers (minimum real times from 10 runs) for one |write()| of |
| 33 // 1032 bytes, one |send()| of 1032 bytes, one |writev()| of 32+1000 bytes, |
| 34 // one |sendmsg()| of 32+1000 bytes, two |write()|s of 32 and 1000 bytes, two |
| 35 // |send()|s of 32 and 1000 bytes: |
| 36 // - Linux: 0.81 s, 0.77 s, 0.87 s, 0.89 s, 1.31 s, 1.22 s |
| 37 // - Mac: 2.21 s, 2.91 s, 2.98 s, 3.08 s, 3.59 s, 4.74 s |
| 38 |
| 39 ssize_t PlatformChannelWrite(PlatformHandle h, |
| 40 const void* bytes, |
| 41 size_t num_bytes) { |
| 42 #if defined(OS_MACOSX) |
| 43 return HANDLE_EINTR(write(h.fd, bytes, num_bytes)); |
| 44 #else |
| 45 return send(h.fd, bytes, num_bytes, MSG_NOSIGNAL); |
| 46 #endif |
| 47 } |
| 48 |
| 49 ssize_t PlatformChannelWritev(PlatformHandle h, |
| 50 struct iovec* iov, |
| 51 size_t num_iov) { |
| 52 #if defined(OS_MACOSX) |
| 53 return HANDLE_EINTR(writev(h.fd, iov, static_cast<int>(num_iov))); |
| 54 #else |
| 55 struct msghdr msg = {}; |
| 56 msg.msg_iov = iov; |
| 57 msg.msg_iovlen = num_iov; |
| 58 return HANDLE_EINTR(sendmsg(h.fd, &msg, MSG_NOSIGNAL)); |
| 59 #endif |
| 60 } |
| 61 |
| 62 } // namespace embedder |
| 63 } // namespace mojo |
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