{"rsdb":{"rid":"383766","subhead":"","postdate":"0","aid":"267298","fid":"78","uid":"1","topic":"1","content":"<div id=\"cnblogs_post_body\" class=\"blogpost-body blogpost-body-html\"> \n <h1 id=\"6cfi27\" class=\"markdown-heading\">1.chan\u6570\u636e\u7ed3\u6784<\/h1> \n <p><img src=\"https:\/\/img2023.cnblogs.com\/blog\/1334624\/202301\/1334624-20230129174021665-1987311571.png\" alt=\"\" loading=\"lazy\" \/><\/p> \n <p>&nbsp;<\/p> \n <p>&nbsp;<img src=\"https:\/\/img2023.cnblogs.com\/blog\/1334624\/202301\/1334624-20230129174040358-1395868946.png\" alt=\"\" loading=\"lazy\" \/><\/p> \n <p>&nbsp;<\/p> \n <p class=\"line\">\u4e00\u4e2achannel\u53ea\u80fd\u4f20\u9012\u4e00\u79cd\u7c7b\u578b\u7684\u503c\uff0c\u7c7b\u578b\u4fe1\u606f\u5b58\u50a8\u5728hchan\u6570\u636e\u7ed3\u6784\u4e2d\u3002<\/p> \n <ul> \n  <li>elemtype\u4ee3\u8868\u7c7b\u578b\uff0c\u7528\u4e8e\u6570\u636e\u4f20\u9012\u8fc7\u7a0b\u4e2d\u7684\u8d4b\u503c\uff1b<\/li> \n  <li>elemsize\u4ee3\u8868\u7c7b\u578b\u5927\u5c0f\uff0c\u7528\u4e8e\u5728buf\u4e2d\u5b9a\u4f4d\u5143\u7d20\u4f4d\u7f6e\u3002<\/li> \n <\/ul> \n <p>\u4e00\u4e2achannel\u540c\u65f6\u4ec5\u5141\u8bb8\u88ab\u4e00\u4e2agoroutine\u8bfb\u5199\uff0c\u4e3a\u7b80\u5355\u8d77\u89c1\uff0c\u672c\u7ae0\u540e\u7eed\u90e8\u5206\u8bf4\u660e\u8bfb\u5199\u8fc7\u7a0b\u65f6\u4e0d\u518d\u6d89\u53ca\u52a0\u9501\u548c\u89e3\u9501\u3002<\/p> \n <h1 id=\"6cfi27\" class=\"markdown-heading\">2.\u521b\u5efaChan<\/h1> \n <p>\u521b\u5efachannel\u7684\u8fc7\u7a0b\u5b9e\u9645\u4e0a\u662f\u521d\u59cb\u5316hchan\u7ed3\u6784\u3002\u5176\u4e2d\u7c7b\u578b\u4fe1\u606f\u548c\u7f13\u51b2\u533a\u957f\u5ea6\u7531make\u8bed\u53e5\u4f20\u5165\uff0cbuf\u7684\u5927\u5c0f\u5219\u4e0e\u5143\u7d20\u5927\u5c0f\u548c\u7f13\u51b2\u533a\u957f\u5ea6\u5171\u540c\u51b3\u5b9a\u3002<\/p> \n <p>&nbsp;makeChan\u6e90\u7801\u5982\u4e0b\uff1a<\/p> \n <pre><span style=\"font-size: 16px\">func makechan(t *chantype, size int) *hchan {<\/span><br \/><span style=\"font-size: 16px\">   elem := t.elem<\/span><br \/><br \/><span style=\"font-size: 16px\">   \/\/ compiler checks this but be safe.<\/span><br \/><span style=\"font-size: 16px\">   if elem.size &gt;= 1&lt;&lt;16 {<\/span><br \/><span style=\"font-size: 16px\">      throw(&quot;makechan: invalid channel element type&quot;)<\/span><br \/><span style=\"font-size: 16px\">   }<\/span><br \/><span style=\"font-size: 16px\">   if hchanSize%maxAlign != 0 || elem.align &gt; maxAlign {<\/span><br \/><span style=\"font-size: 16px\">      throw(&quot;makechan: bad alignment&quot;)<\/span><br \/><span style=\"font-size: 16px\">   }<\/span><br \/><br \/><span style=\"font-size: 16px\">   mem, overflow := math.MulUintptr(elem.size, uintptr(size))<\/span><br \/><span style=\"font-size: 16px\">   if overflow || mem &gt; maxAlloc-hchanSize || size &lt; 0 {<\/span><br \/><span style=\"font-size: 16px\">      panic(plainError(&quot;makechan: size out of range&quot;))<\/span><br \/><span style=\"font-size: 16px\">   }<\/span><br \/><br \/><span style=\"font-size: 16px\">   \/\/ Hchan does not contain pointers interesting for GC when elements stored in buf do not contain pointers.<\/span><br \/><span style=\"font-size: 16px\">   \/\/ buf points into the same allocation, elemtype is persistent.<\/span><br \/><span style=\"font-size: 16px\">   \/\/ SudoG's are referenced from their owning thread so they can't be collected.<\/span><br \/><span style=\"font-size: 16px\">   \/\/ TODO(dvyukov,rlh): Rethink when collector can move allocated objects.<\/span><br \/><span style=\"font-size: 16px\">   var c *hchan<\/span><br \/><span style=\"font-size: 16px\">   switch {<\/span><br \/><span style=\"font-size: 16px\">   \/\/ no buffer \u7684\u573a\u666f\uff0c\u8fd9\u79cd channel \u53ef\u4ee5\u770b\u6210 pipe\uff1b<\/span><br \/><span style=\"font-size: 16px\">   case mem == 0:<\/span><br \/><span style=\"font-size: 16px\">      \/\/ Queue or element size is zero.<\/span><br \/><span style=\"font-size: 16px\">      c = (*hchan)(mallocgc(hchanSize, nil, true))<\/span><br \/><span style=\"font-size: 16px\">      \/\/ Race detector uses this location for synchronization.<\/span><br \/><span style=\"font-size: 16px\">      c.buf = c.raceaddr()<\/span><br \/><span style=\"font-size: 16px\">   case elem.ptrdata == 0:\/\/ channel \u5143\u7d20\u4e0d\u542b\u6307\u9488\u7684\u573a\u666f\uff0c\u90a3\u4e48\u662f\u5206\u914d\u51fa\u4e00\u4e2a\u5927\u5185\u5b58\u5757\uff1b<\/span><br \/><span style=\"font-size: 16px\">      \/\/ Elements do not contain pointers.<\/span><br \/><span style=\"font-size: 16px\">      \/\/ Allocate hchan and buf in one call.<\/span><br \/><span style=\"font-size: 16px\">      c = (*hchan)(mallocgc(hchanSize+mem, nil, true))<\/span><br \/><span style=\"font-size: 16px\">      c.buf = add(unsafe.Pointer(c), hchanSize)<\/span><br \/><span style=\"font-size: 16px\">   default:\/\/ \u9ed8\u8ba4\u573a\u666f\uff0chchan \u7ed3\u6784\u4f53\u548c buffer \u5185\u5b58\u5757\u5355\u72ec\u5206\u914d\uff1b<\/span><br \/><span style=\"font-size: 16px\">      \/\/ Elements contain pointers.<\/span><br \/><span style=\"font-size: 16px\">      c = new(hchan)<\/span><br \/><span style=\"font-size: 16px\">      c.buf = mallocgc(mem, elem, true)<\/span><br \/><span style=\"font-size: 16px\">   }<\/span><br \/><span style=\"font-size: 16px\">   \/\/ channel \u5143\u7d20\u5927\u5c0f\uff0c\u5982\u679c\u662f int\uff0c\u90a3\u4e48\u5c31\u662f 8 \u5b57\u8282\uff1b<\/span><br \/><span style=\"font-size: 16px\">   c.elemsize = uint16(elem.size)<\/span><br \/><span style=\"font-size: 16px\">   \/\/ \u5143\u7d20\u7c7b\u578b\uff0c\u8fd9\u6837\u5c31\u77e5\u9053 channel \u91cc\u9762\u6bcf\u4e2a\u5143\u7d20\u7a76\u7adf\u662f\u5565<\/span><br \/><span style=\"font-size: 16px\">   c.elemtype = elem<\/span><br \/><span style=\"font-size: 16px\">   c.dataqsiz = uint(size)<\/span><br \/><span style=\"font-size: 16px\">   lockInit(&amp;c.lock, lockRankHchan)<\/span><br \/><br \/><span style=\"font-size: 16px\">   if debugChan {<\/span><br \/><span style=\"font-size: 16px\">      print(&quot;makechan: chan=&quot;, c, &quot;; elemsize=&quot;, elem.size, &quot;; dataqsiz=&quot;, size, &quot;\\n&quot;)<\/span><br \/><span style=\"font-size: 16px\">   }<\/span><br \/><span style=\"font-size: 16px\">   return c<\/span><br \/><span style=\"font-size: 16px\">}<br \/>makeChan\u53ea\u4f1a\u521d\u59cb\u5316\u56db\u4e2a\u53c2\u6570\uff1abuf,elemsize,elemtype,dataqsize<br \/>channel\u53d1\u9001\u7684\u4ee3\u7801\u89e3\u6790\u5982\u4e0b\uff1a<br \/><img src=\"https:\/\/img2023.cnblogs.com\/blog\/1334624\/202301\/1334624-20230129181121992-997113313.png\" alt=\"\" loading=\"lazy\" \/><\/span><\/pre> \n <p>&nbsp;<\/p> \n <pre><\/pre> \n <p>&nbsp;<img src=\"https:\/\/img2023.cnblogs.com\/blog\/1334624\/202301\/1334624-20230129181147389-1346297927.png\" alt=\"\" loading=\"lazy\" \/><\/p> \n <p>&nbsp;<\/p> \n <p><img src=\"https:\/\/img2023.cnblogs.com\/blog\/1334624\/202301\/1334624-20230129181213081-678310414.png\" alt=\"\" loading=\"lazy\" \/><\/p> \n <p>&nbsp;<\/p> \n <p>&nbsp;<img src=\"https:\/\/img2023.cnblogs.com\/blog\/1334624\/202301\/1334624-20230129181232922-475148635.png\" alt=\"\" loading=\"lazy\" \/><\/p> \n <p>&nbsp;channel\u63a5\u6536\u6570\u636e\u7684\u4ee3\u7801\u5982\u4e0b\uff1a<\/p> \n <p><img src=\"https:\/\/img2023.cnblogs.com\/blog\/1334624\/202301\/1334624-20230129182247163-1640141181.png\" alt=\"\" loading=\"lazy\" \/><\/p> \n <p>&nbsp;<\/p> \n <p>&nbsp;<img src=\"https:\/\/img2023.cnblogs.com\/blog\/1334624\/202301\/1334624-20230129182302154-251731585.png\" alt=\"\" loading=\"lazy\" \/><\/p> \n <p>&nbsp;<\/p> \n <p>&nbsp;<img src=\"https:\/\/img2023.cnblogs.com\/blog\/1334624\/202301\/1334624-20230129182326741-1578144522.png\" alt=\"\" loading=\"lazy\" \/><\/p> \n <p>&nbsp;<\/p> \n <p>&nbsp;<img src=\"https:\/\/img2023.cnblogs.com\/blog\/1334624\/202301\/1334624-20230129182338649-1390860861.png\" alt=\"\" loading=\"lazy\" \/><\/p> \n <p>&nbsp;<\/p> \n <p>&nbsp;<\/p> \n <p>&nbsp;<\/p> \n <p>&nbsp;<\/p> \n <pre><span style=\"font-size: 16px\">&nbsp;<\/span><\/pre> \n<\/div>","orderid":"0","title":"Go chan\u89e3\u6790","smalltitle":"","mid":"0","fname":"GO","special_id":"0","bak_id":"0","info":"0","hits":"45","pages":"1","comments":"0","posttime":"2023-07-23 13:33:31","list":"1690090411","username":"admin","author":"","copyfrom":"","copyfromurl":"","titlecolor":"","fonttype":"0","titleicon":"0","picurl":"https:\/\/www.cppentry.com\/upload_files\/","ispic":"0","yz":"1","yzer":"","yztime":"0","levels":"0","levelstime":"0","keywords":"<A HREF='https:\/\/www.cppentry.com\/do\/search.php?type=keyword&keyword=chan' target=_blank>chan<\/A> <A HREF='https:\/\/www.cppentry.com\/do\/search.php?type=keyword&keyword=%BD%E2%CE%F6' target=_blank>\u89e3\u6790<\/A>","jumpurl":"","iframeurl":"","style":"","template":"a:3:{s:4:\"head\";s:0:\"\";s:4:\"foot\";s:0:\"\";s:8:\"bencandy\";s:0:\"\";}","target":"0","ip":"119.59.235.169","lastfid":"0","money":"0","buyuser":"","passwd":"","allowdown":"","allowview":"","editer":"","edittime":"0","begintime":"0","endtime":"0","description":"Go chan\u89e3\u6790","lastview":"1694893364","digg_num":"0","digg_time":"0","forbidcomment":"0","ifvote":"0","heart":"","htmlname":"","city_id":"0"},"page":"1"}