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class="search-container"><span></span><input class="search-input" name="search" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><button type="button" id="help-button" title="help">?</button><a id="settings-menu" href="../../settings.html" title="settings"><img width="22" height="22" alt="Change settings" src="../../wheel.svg"></a></div></form></nav></div><section id="main-content" class="content"><div class="example-wrap"><pre class="line-numbers"><span id="1">1</span> <span id="2">2</span> <span id="3">3</span> <span id="4">4</span> <span id="5">5</span> <span id="6">6</span> <span id="7">7</span> <span id="8">8</span> <span id="9">9</span> <span id="10">10</span> <span id="11">11</span> <span id="12">12</span> <span id="13">13</span> <span id="14">14</span> <span id="15">15</span> <span id="16">16</span> <span id="17">17</span> <span id="18">18</span> <span id="19">19</span> <span id="20">20</span> <span 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id="62">62</span> <span id="63">63</span> <span id="64">64</span> <span id="65">65</span> <span id="66">66</span> <span id="67">67</span> <span id="68">68</span> <span id="69">69</span> <span id="70">70</span> <span id="71">71</span> <span id="72">72</span> <span id="73">73</span> <span id="74">74</span> <span id="75">75</span> <span id="76">76</span> <span id="77">77</span> <span id="78">78</span> <span id="79">79</span> <span id="80">80</span> <span id="81">81</span> <span id="82">82</span> <span id="83">83</span> <span id="84">84</span> <span id="85">85</span> <span id="86">86</span> <span id="87">87</span> <span id="88">88</span> <span id="89">89</span> <span id="90">90</span> <span id="91">91</span> <span id="92">92</span> <span id="93">93</span> <span id="94">94</span> <span id="95">95</span> </pre><pre class="rust"><code><span class="kw">use</span> <span class="ident">std::io::Write</span>; <span class="kw">use</span> <span class="ident">anyhow</span>::{<span class="ident">Context</span>, <span class="prelude-ty">Result</span>}; <span class="kw">use</span> <span class="ident">futures_channel::mpsc</span>; <span class="kw">use</span> <span class="ident">abstutil::prettyprint_usize</span>; <span class="doccomment">/// Downloads bytes from a URL. This must be called with a tokio runtime somewhere. The caller</span> <span class="doccomment">/// creates an mpsc channel pair and provides the sender. Progress will be described through it.</span> <span class="kw">pub</span> <span class="kw">async</span> <span class="kw">fn</span> <span class="ident">download_bytes</span><span class="op"><</span><span class="ident">I</span>: <span class="ident">AsRef</span><span class="op"><</span><span class="ident">str</span><span class="op">></span><span class="op">></span>( <span class="ident">url</span>: <span class="ident">I</span>, <span class="ident">post_body</span>: <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">String</span><span class="op">></span>, <span class="ident">progress</span>: <span class="kw-2">&mut</span> <span class="ident">mpsc::Sender</span><span class="op"><</span><span class="ident">String</span><span class="op">></span>, ) -> <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">Vec</span><span class="op"><</span><span class="ident">u8</span><span class="op">></span><span class="op">></span> { <span class="kw">let</span> <span class="ident">url</span> <span class="op">=</span> <span class="ident">url</span>.<span class="ident">as_ref</span>(); <span class="macro">info!</span>(<span class="string">"Downloading {}"</span>, <span class="ident">url</span>); <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">resp</span> <span class="op">=</span> <span class="kw">if</span> <span class="kw">let</span> <span class="prelude-val">Some</span>(<span class="ident">body</span>) <span class="op">=</span> <span class="ident">post_body</span> { <span class="ident">reqwest::Client::new</span>() .<span class="ident">post</span>(<span class="ident">url</span>) .<span class="ident">body</span>(<span class="ident">body</span>) .<span class="ident">send</span>() .<span class="kw">await</span> .<span class="ident">unwrap</span>() } <span class="kw">else</span> { <span class="ident">reqwest::get</span>(<span class="ident">url</span>).<span class="kw">await</span>.<span class="ident">unwrap</span>() }; <span class="ident">resp</span>.<span class="ident">error_for_status_ref</span>() .<span class="ident">with_context</span>(<span class="op">|</span><span class="op">|</span> <span class="ident">url</span>.<span class="ident">to_string</span>())<span class="question-mark">?</span>; <span class="kw">let</span> <span class="ident">total_size</span> <span class="op">=</span> <span class="ident">resp</span>.<span class="ident">content_length</span>().<span class="ident">map</span>(<span class="op">|</span><span class="ident">x</span><span class="op">|</span> <span class="ident">x</span> <span class="kw">as</span> <span class="ident">usize</span>); <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">bytes</span> <span class="op">=</span> <span class="ident">Vec::new</span>(); <span class="kw">while</span> <span class="kw">let</span> <span class="prelude-val">Some</span>(<span class="ident">chunk</span>) <span class="op">=</span> <span class="ident">resp</span>.<span class="ident">chunk</span>().<span class="kw">await</span>.<span class="ident">unwrap</span>() { <span class="comment">// TODO Throttle?</span> <span class="kw">let</span> <span class="ident">msg</span> <span class="op">=</span> <span class="kw">if</span> <span class="kw">let</span> <span class="prelude-val">Some</span>(<span class="ident">n</span>) <span class="op">=</span> <span class="ident">total_size</span> { <span class="macro">format!</span>( <span class="string">"{:.2}% ({} / {} bytes)"</span>, (<span class="ident">bytes</span>.<span class="ident">len</span>() <span class="kw">as</span> <span class="ident">f64</span>) <span class="op">/</span> (<span class="ident">n</span> <span class="kw">as</span> <span class="ident">f64</span>) <span class="op">*</span> <span class="number">100.0</span>, <span class="ident">prettyprint_usize</span>(<span class="ident">bytes</span>.<span class="ident">len</span>()), <span class="ident">prettyprint_usize</span>(<span class="ident">n</span>) ) } <span class="kw">else</span> { <span class="comment">// One example where the HTTP response won't say the response size is the Overpass API</span> <span class="macro">format!</span>( <span class="string">"{} bytes (unknown total size)"</span>, <span class="ident">prettyprint_usize</span>(<span class="ident">bytes</span>.<span class="ident">len</span>()) ) }; <span class="kw">if</span> <span class="kw">let</span> <span class="prelude-val">Err</span>(<span class="ident">err</span>) <span class="op">=</span> <span class="ident">progress</span>.<span class="ident">try_send</span>(<span class="ident">msg</span>) { <span class="macro">warn!</span>(<span class="string">"Couldn't send download progress message: {}"</span>, <span class="ident">err</span>); } <span class="ident">bytes</span>.<span class="ident">write_all</span>(<span class="kw-2">&</span><span class="ident">chunk</span>).<span class="ident">unwrap</span>(); } <span class="macro">println!</span>(); <span class="prelude-val">Ok</span>(<span class="ident">bytes</span>) } <span class="doccomment">/// Download a file from a URL. This must be called with a tokio runtime somewhere. Progress will</span> <span class="doccomment">/// be printed to STDOUT.</span> <span class="kw">pub</span> <span class="kw">async</span> <span class="kw">fn</span> <span class="ident">download_to_file</span><span class="op"><</span><span class="ident">I1</span>: <span class="ident">AsRef</span><span class="op"><</span><span class="ident">str</span><span class="op">></span>, <span class="ident">I2</span>: <span class="ident">AsRef</span><span class="op"><</span><span class="ident">str</span><span class="op">></span><span class="op">></span>( <span class="ident">url</span>: <span class="ident">I1</span>, <span class="ident">post_body</span>: <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">String</span><span class="op">></span>, <span class="ident">path</span>: <span class="ident">I2</span>, ) -> <span class="prelude-ty">Result</span><span class="op"><</span>()<span class="op">></span> { <span class="kw">let</span> (<span class="kw-2">mut</span> <span class="ident">tx</span>, <span class="ident">rx</span>) <span class="op">=</span> <span class="ident">futures_channel::mpsc::channel</span>(<span class="number">1000</span>); <span class="ident">print_download_progress</span>(<span class="ident">rx</span>); <span class="kw">let</span> <span class="ident">bytes</span> <span class="op">=</span> <span class="ident">download_bytes</span>(<span class="ident">url</span>, <span class="ident">post_body</span>, <span class="kw-2">&mut</span> <span class="ident">tx</span>).<span class="kw">await</span><span class="question-mark">?</span>; <span class="kw">let</span> <span class="ident">path</span> <span class="op">=</span> <span class="ident">path</span>.<span class="ident">as_ref</span>(); <span class="op">|</span><span class="op">|</span> -> <span class="prelude-ty">Result</span><span class="op"><</span>()<span class="op">></span> { <span class="ident">fs_err::create_dir_all</span>(<span class="ident">std::path::Path::new</span>(<span class="ident">path</span>).<span class="ident">parent</span>().<span class="ident">unwrap</span>())<span class="question-mark">?</span>; <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">file</span> <span class="op">=</span> <span class="ident">fs_err::File::create</span>(<span class="ident">path</span>)<span class="question-mark">?</span>; <span class="ident">file</span>.<span class="ident">write_all</span>(<span class="kw-2">&</span><span class="ident">bytes</span>)<span class="question-mark">?</span>; <span class="prelude-val">Ok</span>(()) }() .<span class="ident">with_context</span>(<span class="op">|</span><span class="op">|</span> <span class="ident">path</span>.<span class="ident">to_string</span>()) } <span class="doccomment">/// Print download progress to STDOUT. Pass this the receiver, then call download_to_file or</span> <span class="doccomment">/// download_bytes with the sender.</span> <span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">print_download_progress</span>(<span class="kw-2">mut</span> <span class="ident">progress</span>: <span class="ident">mpsc::Receiver</span><span class="op"><</span><span class="ident">String</span><span class="op">></span>) { <span class="ident">tokio::task::spawn_blocking</span>(<span class="kw">move</span> <span class="op">|</span><span class="op">|</span> <span class="kw">loop</span> { <span class="kw">match</span> <span class="ident">progress</span>.<span class="ident">try_next</span>() { <span class="prelude-val">Ok</span>(<span class="prelude-val">Some</span>(<span class="ident">msg</span>)) => { <span class="ident">abstutil::clear_current_line</span>(); <span class="macro">print!</span>(<span class="string">"{}"</span>, <span class="ident">msg</span>); <span class="ident">std::io::stdout</span>().<span class="ident">flush</span>().<span class="ident">unwrap</span>(); } <span class="prelude-val">Ok</span>(<span class="prelude-val">None</span>) => <span class="kw">break</span>, <span class="comment">// Per</span> <span class="comment">// https://docs.rs/futures-channel/0.3.14/futures_channel/mpsc/struct.Receiver.html#method.try_next,</span> <span class="comment">// this means no messages are available yet</span> <span class="prelude-val">Err</span>(<span class="kw">_</span>) => {} } }); } </code></pre></div> </section><section id="search" class="content hidden"></section></div></main><div id="rustdoc-vars" data-root-path="../../" data-current-crate="abstio" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.61.0 (fe5b13d68 2022-05-18)" ></div> </body></html>