Difference between revisions of "Device (C++)"

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<td>  <div class="t-dsc-member-div t-dsc-member-nobold-div"><div><a href="/w/cpp/thread/mutex/mutex" title="cpp/thread/mutex/mutex"> <span class="t-lines"><span>(constructor)</span></span></a></div></div>
 
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<td>  constructs the mutex <br> <span class="t-mark">(public member function)</span> <span class="editsection noprint plainlinks" title="Edit this template"><a rel="nofollow" class="external text" href="http://en.cppreference.com/mwiki/index.php?title=Template:cpp/thread/mutex/dsc_constructor&amp;action=edit">[edit]</a></span>
 
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<td>  <div class="t-dsc-member-div t-dsc-member-nobold-div"><div><a href="/w/cpp/thread/mutex/%7Emutex" title="cpp/thread/mutex/~mutex"> <span class="t-lines"><span>(destructor)</span></span></a></div></div>
 
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<td>  destroys the mutex <br> <span class="t-mark">(public member function)</span> <span class="editsection noprint plainlinks" title="Edit this template"><a rel="nofollow" class="external text" href="http://en.cppreference.com/mwiki/index.php?title=Template:cpp/thread/mutex/dsc_destructor&amp;action=edit">[edit]</a></span>
 
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<td>  <div class="t-dsc-member-div"><div><span class="t-lines"><span>operator=</span></span></div><div><span class="t-lines"><span><span class="t-cmark">[deleted]</span></span></span></div></div>
 
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<td>  not copy-assignable <br> <span class="t-mark">(public member function)</span> <span class="editsection noprint plainlinks" title="Edit this template"><a rel="nofollow" class="external text" href="http://en.cppreference.com/mwiki/index.php?title=Template:cpp/thread/mutex/dsc_operator%3D&amp;action=edit">[edit]</a></span>
 
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<td colspan="2"> <h5> <span class="mw-headline" id="Locking">  Locking </span></h5>
 
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<td>  <div class="t-dsc-member-div"><div><a href="/w/cpp/thread/mutex/lock" title="cpp/thread/mutex/lock"> <span class="t-lines"><span>lock</span></span></a></div></div>
 
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<td>  locks the mutex, blocks if the mutex is not available <br> <span class="t-mark">(public member function)</span> <span class="editsection noprint plainlinks" title="Edit this template"><a rel="nofollow" class="external text" href="http://en.cppreference.com/mwiki/index.php?title=Template:cpp/thread/mutex/dsc_lock&amp;action=edit">[edit]</a></span>
 
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<td>  <div class="t-dsc-member-div"><div><a href="/w/cpp/thread/mutex/try_lock" title="cpp/thread/mutex/try lock"> <span class="t-lines"><span>try_lock</span></span></a></div></div>
 
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<td>  tries to lock the mutex, returns if the mutex is not available <br> <span class="t-mark">(public member function)</span> <span class="editsection noprint plainlinks" title="Edit this template"><a rel="nofollow" class="external text" href="http://en.cppreference.com/mwiki/index.php?title=Template:cpp/thread/mutex/dsc_try_lock&amp;action=edit">[edit]</a></span>
 
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<td>  <div class="t-dsc-member-div"><div><a href="/w/cpp/thread/mutex/unlock" title="cpp/thread/mutex/unlock"> <span class="t-lines"><span>unlock</span></span></a></div></div>
 
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<td>  unlocks the mutex <br> <span class="t-mark">(public member function)</span> <span class="editsection noprint plainlinks" title="Edit this template"><a rel="nofollow" class="external text" href="http://en.cppreference.com/mwiki/index.php?title=Template:cpp/thread/mutex/dsc_unlock&amp;action=edit">[edit]</a></span>
 
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<td colspan="2"> <h5> <span class="mw-headline" id="Native_handle">  Native handle </span></h5>
 
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<td>  <div class="t-dsc-member-div"><div><a href="/w/cpp/thread/mutex/native_handle" title="cpp/thread/mutex/native handle"> <span class="t-lines"><span>native_handle</span></span></a></div></div>
 
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<td>  returns the underlying implementation-defined native handle object <br> <span class="t-mark">(public member function)</span> <span class="editsection noprint plainlinks" title="Edit this template"><a rel="nofollow" class="external text" href="http://en.cppreference.com/mwiki/index.php?title=Template:cpp/thread/mutex/dsc_native_handle&amp;action=edit">[edit]</a></span>
 
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<h3><span class="editsection">[<a href="/mwiki/index.php?title=cpp/thread/mutex&amp;action=edit&amp;section=3" title="Edit section: Notes">edit</a>]</span> <span class="mw-headline" id="Notes">Notes</span></h3>
 
 
<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.
 
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Revision as of 05:45, 26 April 2018

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&section=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.

Run this code
<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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