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Closure: The Definitive Guide
Closure: The Definitive Guide 
这是一个创建于 3082 天前的主题，其中的信息可能已经有所发展或是发生改变。
发生什么事情了？
小弟今天学习webassmbly遇到了这样一件事情。
我在把我 弄好 的wasm模块文件上传到七牛云，再在本地通过fetch来获取这个wasm模块文件进行使用的时候，总是报告编译错误，如下
CompileError: WasmCompile: Compiling WASM function #32 failed:: return[0] expected type i32, found f32.load of type f32 @+3 后来通过断点发现是fetch下来的wasm模块文件有问题，内部的二进制编码变乱了，而且添加了额外的内容，甚至大小从原本的147byte，变成了19Kb。
// 环境检测 var root = this, isBrowserSide = false; if (typeof window !== "undefined" && root === window) { isBrowserSide = true; } // 获取 wasm 并且导入 function fetchAndInstantiateWasm(url, imports) { return fetch(url) // url could be your .wasm file .then(res => { if (res.ok) { if (this.isBrowserSide) return res.arrayBuffer(); else return res.buffer(); } throw new Error(`Unable to fetch Web Assembly file ${url}.`); }) .then(bytes => { // --- 测试用 START --- console.log(bytes) // 在此打印出加载的文件的 bytes 信息 // 当使用本地文件时 // `bytes`为长度为 147 的二进制数组，并且顺利执行程序。 // 而使用上传文件时 // `bytes`为长度为 18670 的二进制数组，并且在下一步`WebAssembly.compile(bytes)`报错， // --- 测试用 END --- return WebAssembly.compile(bytes); }) .then(module => WebAssembly.instantiate(module, imports || {})) .then(instance => instance.exports); } // 调用函数 fetchAndInstantiateWasm("http://osgc6x3up.bkt.clouddn.com/test.wasm") .then(ex => { console.log(ex.add(1, 2)) }); 本地文件 test.wasm(147 byte)
00000000: 00 61 73 6d 01 00 00 00 01 0a 02 60 00 00 60 02 .asm.......`..`. 00000010: 7f 7f 01 7f 03 03 02 00 01 05 03 01 00 01 06 0b ................ 00000020: 02 7f 01 41 00 0b 7f 01 41 00 0b 07 10 02 03 61 ...A....A......a 00000030: 64 64 00 01 06 6d 65 6d 6f 72 79 02 00 08 01 00 dd...memory..... 00000040: 0a 11 02 06 00 23 00 24 01 0b 08 00 20 00 20 01 .....#.$........ 00000050: 6a 0f 0b 0b 0e 01 00 41 08 0b 08 00 00 00 00 00 j......A........ 00000060: 00 00 00 00 2e 04 6e 61 6d 65 01 1a 02 00 12 5f ......name....._ 00000070: 5f 57 41 53 4d 5f 49 4e 49 54 49 41 4c 49 5a 45 _WASM_INITIALIZE 00000080: 52 01 03 61 64 64 02 0b 02 00 00 01 02 00 01 61 R..add.........a 00000090: 01 01 62 ...... ... ... Total 18670 Byte 通过浏览器下载的文件 test.wasm(有省略) (19kb)
00000000: 00 61 73 6d 01 00 00 00 01 3d 0a 60 03 7f 7f 7f .asm.....=.`.... 00000010: 01 7f 60 02 7f 7f 01 7f 60 01 7f 01 7f 60 02 7f ..`.....`....`.. 00000020: 7f 00 60 04 7f 7f 7f 7f 01 7f 60 05 7f 7f 7f 7f ..`.......`..... 00000030: 7f 01 7f 60 03 7f 7f 7f 00 60 00 00 60 01 7f 00 ...`.....`..`... 00000040: 60 03 7d 7d 7d 01 7f 03 26 25 00 00 00 01 00 01 `.}}}...&%...... 00000050: 02 01 03 00 00 00 00 00 04 05 04 00 01 02 02 02 ................ 00000060: 01 02 01 02 06 07 02 08 09 01 02 02 09 01 08 05 ................ 00000070: 03 01 00 01 06 0b 02 7f 01 41 00 0b 7f 01 41 00 .........A....A. 00000080: 0b 07 97 04 1f 06 6d 65 6d 6f 72 79 02 00 06 6d ......memory...m 00000090: 65 6d 63 6d 70 00 00 06 6d 65 6d 63 70 79 00 01 emcmp...memcpy.. 000000a0: 06 6d 65 6d 73 65 74 00 02 0d 63 72 65 61 74 65 .memset...create 000000b0: 5f 6d 73 70 61 63 65 00 03 17 63 72 65 61 74 65 _mspace...create 000000c0: 5f 6d 73 70 61 63 65 5f 77 69 74 68 5f 62 61 73 _mspace_with_bas 000000d0: 65 00 04 19 6d 73 70 61 63 65 5f 74 72 61 63 6b e...mspace_track 000000e0: 5f 6c 61 72 67 65 5f 63 68 75 6e 6b 73 00 05 0e _large_chunks... 000000f0: 64 65 73 74 72 6f 79 5f 6d 73 70 61 63 65 00 06 destroy_mspace.. 00000100: 0d 6d 73 70 61 63 65 5f 6d 61 6c 6c 6f 63 00 07 .mspace_malloc.. 00000110: 0b 6d 73 70 61 63 65 5f 66 72 65 65 00 08 0d 6d .mspace_free...m 00000120: 73 70 61 63 65 5f 63 61 6c 6c 6f 63 00 09 0e 6d space_calloc...m 00000130: 73 70 61 63 65 5f 72 65 61 6c 6c 6f 63 00 0a 17 space_realloc... 00000140: 6d 73 70 61 63 65 5f 72 65 61 6c 6c 6f 63 5f 69 mspace_realloc_i 00000150: 6e 5f 70 6c 61 63 65 00 0c 0f 6d 73 70 61 63 65 n_place...mspace 00000160: 5f 6d 65 6d 61 6c 69 67 6e 00 0d 19 6d 73 70 61 _memalign...mspa 00000170: 63 65 5f 69 6e 64 65 70 65 6e 64 65 6e 74 5f 63 ce_independent_c 00000180: 61 6c 6c 6f 63 十年后
不，并没有十年后，但也是费劲了小弟的一番努力才在写到这的时候，我突然有了头绪。
因为一直都是上传同一个名字的本地文件test.wasm，覆盖的也是七牛云空间上的test.wasm，而正巧之前第一次传入的是一个没有弄好的 19kb 的test.wasm，也就因此造成了这个问题。
简单来说没有覆盖成功。于是小弟以新的文件名再此上传试了试，竟然就成功了！
但是为什么没有覆盖成功呐，
小弟确实按照文档来进行了覆盖上传的操作了啊。
// ...other things above... var overwrite = true; let optiOns= {}; if (overwrite) { options.scope = bucket + ":" + fileName } else { options.scope = bucket } var putPolicy = new qiniu.rs.PutPolicy(options); // ...other things following... 而且在七牛云的工作台上，文件的时间和大小在进行覆盖上传之后也都发生了变化。
就很气
在之后的测试中
在后来的测试中，发现还是无法覆盖上传成功。
就算在控制台中下载文件能够下载到新上传的文件
但是通过外链下载的文件仍然是第一次上传的文件
就如下图所示
我的心情是
BTW,已交工单。
 | 1 mkeith 2017-07-03 04:11:19 +08:00 via iPhone  1 CDN 没更新？ |
 | 3 whiteball OP ``` 116.24.235.38 MISS 186 [02/Jul/2017:16:18:32 +0800] "GET http://osgc6x3up.bkt.clouddn.com/test.wasm HTTP/1.1" 200 19676 "-" "Mozilla/5.0+(Macintosh;+Intel+Mac+OS+X+10_12_1)+AppleWebKit/537.36+(KHTML,+like+Gecko)+Chrome/59.0.3071.115+Safari/537.36" 116.24.235.38 MISS 140 [02/Jul/2017:16:18:52 +0800] "GET http://osgc6x3up.bkt.clouddn.com/test.wasm HTTP/1.1" 200 19680 "-" "node-fetch/1.0+(+https://github.com/bitinn/node-fetch)" 116.24.235.38 MISS 83 [02/Jul/2017:16:18:53 +0800] "GET http://osgc6x3up.bkt.clouddn.com/test.wasm HTTP/1.1" 200 19635 "-" "node-fetch/1.0+(+https://github.com/bitinn/node-fetch)" 116.24.235.38 HIT 57 [02/Jul/2017:16:58:41 +0800] "GET http://osgc6x3up.bkt.clouddn.com/test.wasm HTTP/1.1" 200 19680 "-" "node-fetch/1.0+(+https://github.com/bitinn/node-fetch)" 116.24.235.38 MISS 210 [02/Jul/2017:16:18:32 +0800] "GET http://osgc6x3up.bkt.clouddn.com/test.wasm HTTP/1.1" 200 19715 "-" "Mozilla/5.0+(Macintosh;+Intel+Mac+OS+X+10_12_1)+AppleWebKit/537.36+(KHTML,+like+Gecko)+Chrome/59.0.3071.115+Safari/537.36" 116.24.235.38 MISS 283 [02/Jul/2017:16:18:20 +0800] "GET http://osgc6x3up.bkt.clouddn.com/test.wasm?imageView2/2/w/308/h/210/interlace/1/q/100 HTTP/1.1" 400 936 "-" "Mozilla/5.0+(Macintosh;+Intel+Mac+OS+X+10_12_1)+AppleWebKit/537.36+(KHTML,+like+Gecko)+Chrome/59.0.3071.115+Safari/537.36" 116.24.235.38 HIT 4 [02/Jul/2017:16:57:49 +0800] "GET http://osgc6x3up.bkt.clouddn.com/test.wasm HTTP/1.1" 200 19684 "-" "node-fetch/1.0+(+https://github.com/bitinn/node-fetch)" 116.24.235.38 HIT 20 [02/Jul/2017:16:56:52 +0800] "GET http://osgc6x3up.bkt.clouddn.com/test.wasm HTTP/1.1" 200 19650 "-" "node-fetch/1.0+(+https://github.com/bitinn/node-fetch)" 116.24.235.38 MISS 295 [02/Jul/2017:16:18:19 +0800] "GET http://osgc6x3up.bkt.clouddn.com/test.wasm?imageView2/2/w/308/h/210/interlace/1/q/100 HTTP/1.1" 400 973 "-" "Mozilla/5.0+(Macintosh;+Intel+Mac+OS+X+10_12_1)+AppleWebKit/537.36+(KHTML,+like+Gecko)+Chrome/59.0.3071.115+Safari/537.36" 116.24.235.38 HIT 15 [02/Jul/2017:16:58:42 +0800] "GET http://osgc6x3up.bkt.clouddn.com/test.wasm HTTP/1.1" 200 19611 "-" "node-fetch/1.0+(+https://github.com/bitinn/node-fetch)" 116.24.235.38 MISS 162 [02/Jul/2017:17:06:06 +0800] "GET http://osgc6x3up.bkt.clouddn.com/test.wasm?imageView2/2/w/308/h/210/interlace/1/q/100 HTTP/1.1" 400 909 "-" "Mozilla/5.0+(Macintosh;+Intel+Mac+OS+X+10_12_1)+AppleWebKit/537.36+(KHTML,+like+Gecko)+Chrome/59.0.3071.115+Safari/537.36" 116.24.235.38 MISS 183 [02/Jul/2017:17:06:16 +0800] "GET http://osgc6x3up.bkt.clouddn.com/test.wasm?imageView2/2/w/308/h/210/interlace/1/q/100 HTTP/1.1" 400 888 "-" "Mozilla/5.0+(Macintosh;+Intel+Mac+OS+X+10_12_1)+AppleWebKit/537.36+(KHTML,+like+Gecko)+Chrome/59.0.3071.115+Safari/537.36" 116.24.235.38 HIT 11 [02/Jul/2017:17:33:52 +0800] "GET http://osgc6x3up.bkt.clouddn.com/test.wasm HTTP/1.1" 200 19684 "-" "node-fetch/1.0+(+https://github.com/bitinn/node-fetch)" 116.24.235.38 HIT 0 [02/Jul/2017:17:06:19 +0800] "GET http://osgc6x3up.bkt.clouddn.com/test.wasm HTTP/1.1" 206 19150 "-" "Mozilla/5.0+(Macintosh;+Intel+Mac+OS+X+10_12_1)+AppleWebKit/537.36+(KHTML,+like+Gecko)+Chrome/59.0.3071.115+Safari/537.36" 116.24.235.38 HIT 7 [02/Jul/2017:17:23:04 +0800] "GET http://osgc6x3up.bkt.clouddn.com/test.wasm HTTP/1.1" 200 19684 "-" "node-fetch/1.0+(+https://github.com/bitinn/node-fetch)" 116.24.235.38 MISS 150 [02/Jul/2017:17:16:36 +0800] "GET http://osgc6x3up.bkt.clouddn.com/test.wast HTTP/1.1" 200 1602 "-" "Mozilla/5.0+(Macintosh;+Intel+Mac+OS+X+10_12_1)+AppleWebKit/537.36+(KHTML,+like+Gecko)+Chrome/59.0.3071.115+Safari/537.36" 116.24.235.38 MISS 189 [02/Jul/2017:17:16:36 +0800] "GET http://osgc6x3up.bkt.clouddn.com/test.wast HTTP/1.1" 200 1647 "-" "Mozilla/5.0+(Macintosh;+Intel+Mac+OS+X+10_12_1)+AppleWebKit/537.36+(KHTML,+like+Gecko)+Chrome/59.0.3071.115+Safari/537.36" 116.24.235.38 HIT 55 [02/Jul/2017:17:08:05 +0800] "GET http://osgc6x3up.bkt.clouddn.com/test.wasm HTTP/1.1" 200 19652 "-" "node-fetch/1.0+(+https://github.com/bitinn/node-fetch)" 116.24.235.38 MISS 145 [02/Jul/2017:17:06:16 +0800] "GET http://osgc6x3up.bkt.clouddn.com/test.wasm?imageView2/2/w/308/h/210/interlace/1/q/100 HTTP/1.1" 400 844 "-" "Mozilla/5.0+(Macintosh;+Intel+Mac+OS+X+10_12_1)+AppleWebKit/537.36+(KHTML,+like+Gecko)+Chrome/59.0.3071.115+Safari/537.36" 116.24.235.38 HIT 51 [02/Jul/2017:17:09:01 +0800] "GET http://osgc6x3up.bkt.clouddn.com/test.wasm HTTP/1.1" 200 19722 "-" "node-fetch/1.0+(+https://github.com/bitinn/node-fetch)" 116.24.235.38 HIT 62 [02/Jul/2017:17:05:01 +0800] "GET http://osgc6x3up.bkt.clouddn.com/test.wasm HTTP/1.1" 200 19650 "-" "node-fetch/1.0+(+https://github.com/bitinn/node-fetch)" 116.24.235.38 HIT 0 [02/Jul/2017:17:06:19 +0800] "GET http://osgc6x3up.bkt.clouddn.com/test.wasm HTTP/1.1" 206 1026 "-" "Mozilla/5.0+(Macintosh;+Intel+Mac+OS+X+10_12_1)+AppleWebKit/537.36+(KHTML,+like+Gecko)+Chrome/59.0.3071.115+Safari/537.36" 116.24.235.38 HIT 130 [02/Jul/2017:17:08:05 +0800] "GET http://osgc6x3up.bkt.clouddn.com/test.wasm HTTP/1.1" 200 19721 "-" "node-fetch/1.0+(+https://github.com/bitinn/node-fetch)" 116.24.235.38 HIT 0 [02/Jul/2017:17:05:53 +0800] "GET http://osgc6x3up.bkt.clouddn.com/test.wasm HTTP/1.1" 200 19684 "-" "node-fetch/1.0+(+https://github.com/bitinn/node-fetch)" 116.24.235.38 HIT 0 [02/Jul/2017:17:14:13 +0800] "GET http://osgc6x3up.bkt.clouddn.com/test.wasm HTTP/1.1" 200 19650 "-" "node-fetch/1.0+(+https://github.com/bitinn/node-fetch)" 116.24.235.38 HIT 49 [02/Jul/2017:17:15:32 +0800] "GET http://osgc6x3up.bkt.clouddn.com/test.wasm HTTP/1.1" 200 19652 "-" "node-fetch/1.0+(+https://github.com/bitinn/node-fetch)" 116.24.235.38 HIT 41 [02/Jul/2017:17:06:54 +0800] "GET http://osgc6x3up.bkt.clouddn.com/test.wasm HTTP/1.1" 200 19638 "-" "node-fetch/1.0+(+https://github.com/bitinn/node-fetch)" 116.24.235.38 HIT 0 [02/Jul/2017:17:09:01 +0800] "GET http://osgc6x3up.bkt.clouddn.com/test.wasm HTTP/1.1" 200 19652 "-" "node-fetch/1.0+(+https://github.com/bitinn/node-fetch)" 116.24.235.38 HIT 72 [02/Jul/2017:17:15:31 +0800] "GET http://osgc6x3up.bkt.clouddn.com/test.wasm HTTP/1.1" 200 19723 "-" "node-fetch/1.0+(+https://github.com/bitinn/node-fetch)" 116.24.235.38 HIT 13 [02/Jul/2017:17:11:52 +0800] "GET http://osgc6x3up.bkt.clouddn.com/test.wasm HTTP/1.1" 200 19650 "-" "node-fetch/1.0+(+https://github.com/bitinn/node-fetch)" 116.24.235.38 HIT 21 [02/Jul/2017:17:32:43 +0800] "GET http://osgc6x3up.bkt.clouddn.com/test.wasm HTTP/1.1" 200 19682 "-" "node-fetch/1.0+(+https://github.com/bitinn/node-fetch)" 116.24.235.38 MISS 237 [02/Jul/2017:17:06:06 +0800] "GET http://osgc6x3up.bkt.clouddn.com/test.wasm?imageView2/2/w/308/h/210/interlace/1/q/100 HTTP/1.1" 400 953 "-" "Mozilla/5.0+(Macintosh;+Intel+Mac+OS+X+10_12_1)+AppleWebKit/537.36+(KHTML,+like+Gecko)+Chrome/59.0.3071.115+Safari/537.36" ``` CDN 的日志 |
 | 4 ovear 2017-07-03 04:22:12 +08:00 via Android 1 在后台刷新缓存 |
| 5 whiteball OP @ovear 不是很懂，是这样么...不过弄完还是不行诶。  |
 | 6 libook 2017-07-03 09:23:18 +08:00 via Android 1 Cdn 存在的意义之一 ， 就是能让任何地区的任何量级的用户 都能流畅地访问到资源， 所以 cdn 在很多地区都会有大量的分布式节点服务器。覆盖老文件，cdn 需要同步这些节点， 受限于速度、成本和任务量等因素，cdn 通常难以做到及时更新。七牛官方的建议是尽可能不修改已经上传的文件，但如果一定要修改，就要等待七牛每七日一次的节点同步，或者手动去七牛后台刷新，刷新文件数量和频率都是有限制的。所以 cdn 的最佳实践是，修改文件要同时修改文件名（如 abc-1.0.bin ），以新文件的形式上传 cdn，客户端动态从应用服务器上获取最新的 url，访问七牛 cdn 上的最新上传的文件。 另外七牛上也可以配置客户端缓存的时长，如果是浏览器或任何严格遵循 http 标准的客户端都会按照数据头的缓存时常进行本地缓存。 |
 | 7 xmadi 2017-07-03 09:50:47 +08:00 via iPhone 1 cdn 就是这样的 缓存很多 每次上传改名字吧 |
 | 10 indooorsman 2017-07-03 11:45:53 +08:00 via Android 1 看到标题第一反应就是没刷新 cdn 缓存… 七牛提供刷新缓存的接口，也有 web 界面可以刷新的 每次上传改名是个好主意 |
 | 11 whiteball OP @indooorsman 老司机就是有经验啊。 =，=突然感觉有点丢人...果然这锅还是得自己来背。 文档写得也挺清楚的： https://developer.qiniu.com/fusion/kb/1325/refresh-the-cache-and-the-effect-of-time |
 | 12 codingkiller 2017-07-03 12:05:55 +08:00 CDN，基本功。 |
 | 13 anyele 2017-07-03 12:12:01 +08:00 via Android 十年后 |
 | 14 SourceMan 2017-07-03 12:32:02 +08:00 via iPhone 哈哈哈，缓存问题 |
 | 15 ty89 2017-07-03 13:38:05 +08:00 废话写了一大堆 所以楼主你 http 的基础知识是看 a 片学的吗 10 年后： 《震惊！修改了 css 文件后显示效果竟然没有丝毫变化，原因让所有人不瞪口呆...》 |
 | 16 mingyun 2017-07-03 22:51:57 +08:00 已解决 v2 可编辑了? |
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