Difference between revisions of "Device (C++)"
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<p><code>std::mutex</code> is usually not accessed directly: <span class="t-lc"><a href="/w/cpp/thread/unique_lock" title="cpp/thread/unique lock">std::unique_lock</a></span>, <span class="t-lc"><a href="/w/cpp/thread/lock_guard" title="cpp/thread/lock guard">std::lock_guard</a></span>, <span class="t-rev-inl t-since-cxx17"><span> or <span class="t-lc">std::scoped_lock</span> </span> <span><span class="t-mark-rev t-since-cxx17">(since C++17)</span></span></span> manage locking in a more exception-safe manner. | <p><code>std::mutex</code> is usually not accessed directly: <span class="t-lc"><a href="/w/cpp/thread/unique_lock" title="cpp/thread/unique lock">std::unique_lock</a></span>, <span class="t-lc"><a href="/w/cpp/thread/lock_guard" title="cpp/thread/lock guard">std::lock_guard</a></span>, <span class="t-rev-inl t-since-cxx17"><span> or <span class="t-lc">std::scoped_lock</span> </span> <span><span class="t-mark-rev t-since-cxx17">(since C++17)</span></span></span> manage locking in a more exception-safe manner. | ||
</p> | </p> |
Revision as of 05:45, 26 April 2018
Contents
Neuro::Device
Defined in header <device/device.h>
class Device final;
The Device class is an abstraction for NeuroMD BLE devices. This abstraction provides functions for changing of device state by executing commands and setting parameters. Each device have different sets of supported commands and parameters, Device class has functions designed to get information about these sets.
Member functions
(constructor)[private] | constructs device, inaccessible from user code, new device object could be constructed only by DeviceScanner instance |
(destructor) | destroys device |
operator=[deleted] | not copy assignable |
Supported features | |
---|---|
channels | returns information about channels which could be created with this device, contains information about channels types and names |
commands | returns vector containing supported commands |
parameters | returns |
Non-member functions
checkHasChannel | returns true if device has channel with same channel information |
checkHasCommand | returns true if device supports specified command |
checkHasParameter | returns true if device has specified parameter |
countChannelsWithType | returns number of channels with specified type in channel info section |
getParameterAccess | if device has specified parameter returns access modifier for it, otherwise throws |
Notes
std::mutex
is usually not accessed directly: <a href="/w/cpp/thread/unique_lock" title="cpp/thread/unique lock">std::unique_lock</a>, <a href="/w/cpp/thread/lock_guard" title="cpp/thread/lock guard">std::lock_guard</a>, or std::scoped_lock (since C++17) manage locking in a more exception-safe manner.
[<a href="/mwiki/index.php?title=cpp/thread/mutex&action=edit§ion=4" title="Edit section: Example">edit</a>] Example
This example shows how a mutex
can be used to protect a <a href="/w/cpp/container/map" title="cpp/container/map">std::map</a> shared between two threads.
<span class="co2">#include <iostream></span> <span class="co2">#include <map></span> <span class="co2">#include <string></span> <span class="co2">#include <chrono></span> <span class="co2">#include <thread></span> <span class="co2">#include <mutex></span> <a href="http://en.cppreference.com/w/cpp/container/map"><span class="kw1281">std::<span class="me2">map</span></span></a><span class="sy1"><</span><a href="http://en.cppreference.com/w/cpp/string/basic_string"><span class="kw1230">std::<span class="me2">string</span></span></a>, <a href="http://en.cppreference.com/w/cpp/string/basic_string"><span class="kw1230">std::<span class="me2">string</span></span></a><span class="sy1">></span> g_pages<span class="sy4">;</span> std<span class="sy4">::</span><span class="me2">mutex</span> g_pages_mutex<span class="sy4">;</span> <span class="kw4">void</span> save_page<span class="br0">(</span><span class="kw4">const</span> <a href="http://en.cppreference.com/w/cpp/string/basic_string"><span class="kw1230">std::<span class="me2">string</span></span></a> <span class="sy3">&</span>url<span class="br0">)</span> <span class="br0">{</span> <span class="co1">// simulate a long page fetch</span> <a href="http://en.cppreference.com/w/cpp/thread/sleep_for"><span class="kw2149">std::<span class="me2">this_thread</span><span class="sy4">::</span><span class="me2">sleep_for</span></span></a><span class="br0">(</span><a href="http://en.cppreference.com/w/cpp/chrono/duration"><span class="kw997">std::<span class="me2">chrono</span><span class="sy4">::</span><span class="me2">seconds</span></span></a><span class="br0">(</span><span class="nu0">2</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span> <a href="http://en.cppreference.com/w/cpp/string/basic_string"><span class="kw1230">std::<span class="me2">string</span></span></a> result <span class="sy1">=</span> <span class="st0">"fake content"</span><span class="sy4">;</span> <a href="http://en.cppreference.com/w/cpp/thread/lock_guard"><span class="kw2165">std::<span class="me2">lock_guard</span></span></a><span class="sy1"><</span>std<span class="sy4">::</span><span class="me2">mutex</span><span class="sy1">></span> guard<span class="br0">(</span>g_pages_mutex<span class="br0">)</span><span class="sy4">;</span> g_pages<span class="br0">[</span>url<span class="br0">]</span> <span class="sy1">=</span> result<span class="sy4">;</span> <span class="br0">}</span> <span class="kw4">int</span> main<span class="br0">(</span><span class="br0">)</span> <span class="br0">{</span> <a href="http://en.cppreference.com/w/cpp/thread/thread"><span class="kw2146">std::<span class="me2">thread</span></span></a> t1<span class="br0">(</span>save_page, <span class="st0">"http://foo"</span><span class="br0">)</span><span class="sy4">;</span> <a href="http://en.cppreference.com/w/cpp/thread/thread"><span class="kw2146">std::<span class="me2">thread</span></span></a> t2<span class="br0">(</span>save_page, <span class="st0">"http://bar"</span><span class="br0">)</span><span class="sy4">;</span> t1.<span class="me1">join</span><span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span> t2.<span class="me1">join</span><span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span> <span class="co1">// safe to access g_pages without lock now, as the threads are joined</span> <span class="kw1">for</span> <span class="br0">(</span><span class="kw4">const</span> <span class="kw4">auto</span> <span class="sy3">&</span>pair <span class="sy4">:</span> g_pages<span class="br0">)</span> <span class="br0">{</span> <a href="http://en.cppreference.com/w/cpp/io/cout"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> pair.<span class="me1">first</span> <span class="sy1"><<</span> <span class="st0">" => "</span> <span class="sy1"><<</span> pair.<span class="me1">second</span> <span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</span><span class="sy4">;</span> <span class="br0">}</span> <span class="br0">}</span>
Output:
http://bar => fake content http://foo => fake content
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