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Slice 实现原理分析

Posted by 夏泽民 Apr 7, 2020

众所周知，在golang中，slice（切片）是我们最常使用到的一种数据结构，是一种可变长度的数组，本篇文章我们主要结合源码来介绍一下slice的底层实现，以及在使用slice时的一些注意事项。 Slice结构体 首先我们来看一段代码： package main import ( “fmt” “unsafe” ) func main() { var a int var b int8 var c int16 var d int32 var e int64 slice := make([]int, 0) slice = append(slice, 1) fmt.Printf(“int:%d\nint8:%d\nint16:%d\nint32:%d\nint64:%d\n”, unsafe.Sizeof(a), unsafe.Sizeof(b), unsafe.Sizeof(c), unsafe.Sizeof(d), unsafe.Sizeof(e)) fmt.Printf(“slice:%d”, unsafe.Sizeof(slice)) } 该程序输出golang中常用数据类型占多少byte，输出结果是：

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stream_set_timeout

Posted by 夏泽民 Apr 3, 2020

PHP函数stream_set_timeout（Stream Functions）作用于读取流时的时间控制。fsockopen函数的timeout只管创建连接时的超时，对于连接后读取流时的超时，则需要用到 stream_set_timeout函数。由于国内的网络环境不是很稳定，尤其是连接国外的时候，不想程序出现Fatal error: Maximum execution time of 30 seconds exceeded in …的错误，该函数尤其有用。stream_set_timeout需配合stream_get_meta_data使用，如果没有timeout， stream_get_meta_data返回数组中time_out为空，反之为1，可根据此判断是否超时。另外由于PHP默认的Maximum execution time为30秒，这是一次执行周期的时间，为了不出现上述的Fatal error，还需要设置一个总的读取流的时间 $server=”www.yahoo.com”;
$port = 80;

$data=”GET / HTTP/1.0rn”;
$data.=”Connection: Closern”;
$data.=”User-Agent: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1)rnrn”;

$start_time = time();
$fp=fsockopen($server, $port, $errno, $errstr, 5);
if (!$fp) {
die(“Connect Timeout.n”);
} else {
stream_set_blocking($fp, True);
stream_set_timeout($fp, 3);

fputs($fp, “$data”);
while (!feof($fp)) {
$text .= fread($fp, 2000);

$diff = time() - $start_time;
if ($diff > 24) {
die(“Timeout!n”);
}

$status = stream_get_meta_data($fp);
if ($status[’timed_out’]) {
die(“Stream Timeout!n”);
}
}
}

fclose($fp);

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__destruct与register_shutdown_function执行的先后顺序

Posted by 夏泽民 Apr 3, 2020

根据php手册的解析。

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Generating Go code in Kubebuilder style

Posted by 夏泽民 Apr 3, 2020

Generally speaking, code generation is the process of producing code from some sort of abstract description. Although this is not a very expressive description, almost everyone has some sort of understanding of code generation. For example, in the cloud native ecosystem generating code from Protobuf or OpenAPI descriptors is quite common.

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enable_file_override

Posted by 夏泽民 Apr 3, 2020

opcache.enable_file_override boolean

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