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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/shell/data_pipe_peek.h" | |
| 6 | |
| 7 #include <stddef.h> | |
| 8 #include <stdint.h> | |
| 9 | |
| 10 #include <algorithm> | |
| 11 | |
| 12 #include "base/bind.h" | |
| 13 #include "base/macros.h" | |
| 14 | |
| 15 namespace mojo { | |
| 16 namespace shell { | |
| 17 | |
| 18 namespace { | |
| 19 | |
| 20 // Sleep for as long as max_sleep_micros if the deadline hasn't been reached | |
| 21 // and the number of bytes read is still increasing. Returns true if sleep | |
| 22 // was actually called. | |
| 23 // | |
| 24 // This class is a substitute for being able to wait until N bytes are available | |
| 25 // from a data pipe. The MaybeSleep method is called when num_bytes_read are | |
| 26 // available but more are needed by the Peek operation. If a second | |
| 27 // Peek operation finds the same number of bytes after sleeping we assume | |
| 28 // that there's no point in trying again. | |
| 29 // TODO(hansmuller): this heuristic is weak. crbug.com/429377 | |
| 30 class PeekSleeper { | |
| 31 public: | |
| 32 explicit PeekSleeper(MojoTimeTicks deadline) | |
| 33 : deadline_(deadline), | |
| 34 last_number_bytes_read_(0) {} | |
| 35 | |
| 36 bool MaybeSleep(uint32_t num_bytes_read) { | |
| 37 if (num_bytes_read > 0 && last_number_bytes_read_ >= num_bytes_read) | |
| 38 return false; | |
| 39 last_number_bytes_read_ = num_bytes_read; | |
| 40 | |
| 41 MojoTimeTicks now(GetTimeTicksNow()); | |
| 42 if (now > deadline_) | |
| 43 return false; | |
| 44 | |
| 45 MojoTimeTicks sleep_time = | |
| 46 (deadline_ == 0) ? kMaxSleepMicros | |
| 47 : std::min<int64_t>(deadline_ - now, kMaxSleepMicros); | |
| 48 base::PlatformThread::Sleep(base::TimeDelta::FromMicroseconds(sleep_time)); | |
| 49 return true; | |
| 50 } | |
| 51 | |
| 52 private: | |
| 53 static const MojoTimeTicks kMaxSleepMicros = 1000 * 10; // 10 ms | |
| 54 | |
| 55 const MojoTimeTicks deadline_; // 0 => MOJO_DEADLINE_INDEFINITE | |
| 56 uint32_t last_number_bytes_read_; | |
| 57 | |
| 58 DISALLOW_COPY_AND_ASSIGN(PeekSleeper); | |
| 59 }; | |
| 60 | |
| 61 const MojoTimeTicks PeekSleeper::kMaxSleepMicros; | |
| 62 | |
| 63 enum PeekStatus { kSuccess, kFail, kKeepReading }; | |
| 64 typedef const base::Callback<PeekStatus(const void*, uint32_t, std::string*)>& | |
| 65 PeekFunc; | |
| 66 | |
| 67 // When data is available on source, call peek_func and then either return true | |
| 68 // and value, continue waiting for enough data to satisfy peek_func, or fail | |
| 69 // and return false. Fail if the timeout is exceeded. | |
| 70 // This function is not guaranteed to work correctly if applied to a data pipe | |
| 71 // that's already been read from. | |
| 72 bool BlockingPeekHelper(DataPipeConsumerHandle source, | |
| 73 std::string* value, | |
| 74 MojoDeadline timeout, | |
| 75 PeekFunc peek_func) { | |
| 76 DCHECK(value); | |
| 77 value->clear(); | |
| 78 | |
| 79 MojoTimeTicks deadline = | |
| 80 (timeout == MOJO_DEADLINE_INDEFINITE) | |
| 81 ? 0 | |
| 82 : 1 + GetTimeTicksNow() + static_cast<MojoTimeTicks>(timeout); | |
| 83 PeekSleeper sleeper(deadline); | |
| 84 | |
| 85 MojoResult result; | |
| 86 do { | |
| 87 const void* buffer; | |
| 88 uint32_t num_bytes; | |
| 89 result = | |
| 90 BeginReadDataRaw(source, &buffer, &num_bytes, MOJO_READ_DATA_FLAG_NONE); | |
| 91 | |
| 92 if (result == MOJO_RESULT_OK) { | |
| 93 PeekStatus status = peek_func.Run(buffer, num_bytes, value); | |
| 94 CHECK_EQ(EndReadDataRaw(source, 0), MOJO_RESULT_OK); | |
| 95 switch (status) { | |
| 96 case PeekStatus::kSuccess: | |
| 97 return true; | |
| 98 case PeekStatus::kFail: | |
| 99 return false; | |
| 100 case PeekStatus::kKeepReading: | |
| 101 break; | |
| 102 } | |
| 103 if (!sleeper.MaybeSleep(num_bytes)) | |
| 104 return false; | |
| 105 } else if (result == MOJO_RESULT_SHOULD_WAIT) { | |
| 106 MojoTimeTicks now(GetTimeTicksNow()); | |
| 107 if (timeout == MOJO_DEADLINE_INDEFINITE || now < deadline) | |
| 108 result = | |
| 109 Wait(source, MOJO_HANDLE_SIGNAL_READABLE, deadline - now, nullptr); | |
| 110 } | |
| 111 } while (result == MOJO_RESULT_OK); | |
| 112 | |
| 113 return false; | |
| 114 } | |
| 115 | |
| 116 PeekStatus PeekLine(size_t max_line_length, | |
| 117 const void* buffer, | |
| 118 uint32_t buffer_num_bytes, | |
| 119 std::string* line) { | |
| 120 const char* p = static_cast<const char*>(buffer); | |
| 121 size_t max_p_index = std::min<size_t>(buffer_num_bytes, max_line_length); | |
| 122 for (size_t i = 0; i < max_p_index; i++) { | |
| 123 if (p[i] == '\n') { | |
| 124 *line = std::string(p, i + 1); // Include the trailing newline. | |
| 125 return PeekStatus::kSuccess; | |
| 126 } | |
| 127 } | |
| 128 return (buffer_num_bytes >= max_line_length) ? PeekStatus::kFail | |
| 129 : PeekStatus::kKeepReading; | |
| 130 } | |
| 131 | |
| 132 PeekStatus PeekNBytes(size_t bytes_length, | |
| 133 const void* buffer, | |
| 134 uint32_t buffer_num_bytes, | |
| 135 std::string* bytes) { | |
| 136 if (buffer_num_bytes >= bytes_length) { | |
| 137 const char* p = static_cast<const char*>(buffer); | |
| 138 *bytes = std::string(p, bytes_length); | |
| 139 return PeekStatus::kSuccess; | |
| 140 } | |
| 141 return PeekStatus::kKeepReading; | |
| 142 } | |
| 143 | |
| 144 } // namespace | |
| 145 | |
| 146 bool BlockingPeekNBytes(DataPipeConsumerHandle source, | |
| 147 std::string* bytes, | |
| 148 size_t bytes_length, | |
| 149 MojoDeadline timeout) { | |
| 150 PeekFunc peek_nbytes = base::Bind(PeekNBytes, bytes_length); | |
| 151 return BlockingPeekHelper(source, bytes, timeout, peek_nbytes); | |
| 152 } | |
| 153 | |
| 154 bool BlockingPeekLine(DataPipeConsumerHandle source, | |
| 155 std::string* line, | |
| 156 size_t max_line_length, | |
| 157 MojoDeadline timeout) { | |
| 158 PeekFunc peek_line = base::Bind(PeekLine, max_line_length); | |
| 159 return BlockingPeekHelper(source, line, timeout, peek_line); | |
| 160 } | |
| 161 | |
| 162 } // namespace shell | |
| 163 } // namespace mojo | |
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Issue 1701933004:
Remove the old package manager (Closed)
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