文章
Jingwei Wang · 九月 27, 2021
html {overflow-x: initial !important;}:root { --bg-color: #ffffff; --text-color: #333333; --select-text-bg-color: #B5D6FC; --select-text-font-color: auto; --monospace: "Lucida Console",Consolas,"Courier",monospace; --title-bar-height: 20px; }
.mac-os-11 { --title-bar-height: 28px; }
html { font-size: 14px; background-color: var(--bg-color); color: var(--text-color); font-family: "Helvetica Neue", Helvetica, Arial, sans-serif; -webkit-font-smoothing: antialiased; }
body { margin: 0px; padding: 0px; height: auto; inset: 0px; font-size: 1rem; line-height: 1.42857143; overflow-x: hidden; background-image: inherit; background-size: inherit; background-attachment: inherit; background-origin: inherit; background-clip: inherit; background-color: inherit; tab-size: 4; background-position: inherit; background-repeat: inherit; }
iframe { margin: auto; }
a.url { word-break: break-all; }
a:active, a:hover { outline: 0px; }
.in-text-selection, ::selection { text-shadow: none; background: var(--select-text-bg-color); color: var(--select-text-font-color); }
#write { margin: 0px auto; height: auto; width: inherit; word-break: normal; word-wrap: break-word; position: relative; white-space: normal; overflow-x: visible; padding-top: 36px; }
#write.first-line-indent p { text-indent: 2em; }
#write.first-line-indent li p, #write.first-line-indent p * { text-indent: 0px; }
#write.first-line-indent li { margin-left: 2em; }
.for-image #write { padding-left: 8px; padding-right: 8px; }
body.typora-export { padding-left: 30px; padding-right: 30px; }
.typora-export .footnote-line, .typora-export li, .typora-export p { white-space: pre-wrap; }
.typora-export .task-list-item input { pointer-events: none; }
@media screen and (max-width: 500px) {
body.typora-export { padding-left: 0px; padding-right: 0px; }
#write { padding-left: 20px; padding-right: 20px; }
.CodeMirror-sizer { margin-left: 0px !important; }
.CodeMirror-gutters { display: none !important; }
}
#write li > figure:last-child { margin-bottom: 0.5rem; }
#write ol, #write ul { position: relative; }
img { max-width: 100%; vertical-align: middle; image-orientation: from-image; }
button, input, select, textarea { color: inherit; font-family: inherit; font-size: inherit; font-style: inherit; font-variant-caps: inherit; font-weight: inherit; font-stretch: inherit; line-height: inherit; }
input[type="checkbox"], input[type="radio"] { line-height: normal; padding: 0px; }
*, ::after, ::before { box-sizing: border-box; }
#write h1, #write h2, #write h3, #write h4, #write h5, #write h6, #write p, #write pre { width: inherit; }
#write h1, #write h2, #write h3, #write h4, #write h5, #write h6, #write p { position: relative; }
p { line-height: inherit; }
h1, h2, h3, h4, h5, h6 { break-after: avoid-page; break-inside: avoid; orphans: 4; }
p { orphans: 4; }
h1 { font-size: 2rem; }
h2 { font-size: 1.8rem; }
h3 { font-size: 1.6rem; }
h4 { font-size: 1.4rem; }
h5 { font-size: 1.2rem; }
h6 { font-size: 1rem; }
.md-math-block, .md-rawblock, h1, h2, h3, h4, h5, h6, p { margin-top: 1rem; margin-bottom: 1rem; }
.hidden { display: none; }
.md-blockmeta { color: rgb(204, 204, 204); font-weight: 700; font-style: italic; }
a { cursor: pointer; }
sup.md-footnote { padding: 2px 4px; background-color: rgba(238, 238, 238, 0.7); color: rgb(85, 85, 85); border-top-left-radius: 4px; border-top-right-radius: 4px; border-bottom-right-radius: 4px; border-bottom-left-radius: 4px; cursor: pointer; }
sup.md-footnote a, sup.md-footnote a:hover { color: inherit; text-transform: inherit; text-decoration: inherit; }
#write input[type="checkbox"] { cursor: pointer; width: inherit; height: inherit; }
figure { overflow-x: auto; margin: 1.2em 0px; max-width: calc(100% + 16px); padding: 0px; }
figure > table { margin: 0px; }
tr { break-inside: avoid; break-after: auto; }
thead { display: table-header-group; }
table { border-collapse: collapse; border-spacing: 0px; width: 100%; overflow: auto; break-inside: auto; text-align: left; }
table.md-table td { min-width: 32px; }
.CodeMirror-gutters { border-right-width: 0px; background-color: inherit; }
.CodeMirror-linenumber { }
.CodeMirror { text-align: left; }
.CodeMirror-placeholder { opacity: 0.3; }
.CodeMirror pre { padding: 0px 4px; }
.CodeMirror-lines { padding: 0px; }
div.hr:focus { cursor: none; }
#write pre { white-space: pre-wrap; }
#write.fences-no-line-wrapping pre { white-space: pre; }
#write pre.ty-contain-cm { white-space: normal; }
.CodeMirror-gutters { margin-right: 4px; }
.md-fences { font-size: 0.9rem; display: block; break-inside: avoid; text-align: left; overflow: visible; white-space: pre; background-image: inherit; background-size: inherit; background-attachment: inherit; background-origin: inherit; background-clip: inherit; background-color: inherit; position: relative !important; background-position: inherit; background-repeat: inherit; }
.md-fences-adv-panel { width: 100%; margin-top: 10px; text-align: center; padding-top: 0px; padding-bottom: 8px; overflow-x: auto; }
#write .md-fences.mock-cm { white-space: pre-wrap; }
.md-fences.md-fences-with-lineno { padding-left: 0px; }
#write.fences-no-line-wrapping .md-fences.mock-cm { white-space: pre; overflow-x: auto; }
.md-fences.mock-cm.md-fences-with-lineno { padding-left: 8px; }
.CodeMirror-line, twitterwidget { break-inside: avoid; }
.footnotes { opacity: 0.8; font-size: 0.9rem; margin-top: 1em; margin-bottom: 1em; }
.footnotes + .footnotes { margin-top: 0px; }
.md-reset { margin: 0px; padding: 0px; border: 0px; outline: 0px; vertical-align: top; text-decoration: none; text-shadow: none; float: none; position: static; width: auto; height: auto; white-space: nowrap; cursor: inherit; line-height: normal; font-weight: 400; text-align: left; box-sizing: content-box; direction: ltr; background-position: 0px 0px; }
li div { padding-top: 0px; }
blockquote { margin: 1rem 0px; }
li .mathjax-block, li p { margin: 0.5rem 0px; }
li blockquote { margin: 1rem 0px; }
li { margin: 0px; position: relative; }
blockquote > :last-child { margin-bottom: 0px; }
blockquote > :first-child, li > :first-child { margin-top: 0px; }
.footnotes-area { color: rgb(136, 136, 136); margin-top: 0.714rem; padding-bottom: 0.143rem; white-space: normal; }
#write .footnote-line { white-space: pre-wrap; }
@media print {
body, html { border: 1px solid transparent; height: 99%; break-after: avoid; break-before: avoid; font-variant-ligatures: no-common-ligatures; }
#write { margin-top: 0px; padding-top: 0px; border-color: transparent !important; }
.typora-export * { -webkit-print-color-adjust: exact; }
.typora-export #write { break-after: avoid; }
.typora-export #write::after { height: 0px; }
.is-mac table { break-inside: avoid; }
.typora-export-show-outline .typora-export-sidebar { display: none; }
}
.footnote-line { margin-top: 0.714em; font-size: 0.7em; }
a img, img a { cursor: pointer; }
pre.md-meta-block { font-size: 0.8rem; min-height: 0.8rem; white-space: pre-wrap; background-color: rgb(204, 204, 204); display: block; overflow-x: hidden; }
p > .md-image:only-child:not(.md-img-error) img, p > img:only-child { display: block; margin: auto; }
#write.first-line-indent p > .md-image:only-child:not(.md-img-error) img { left: -2em; position: relative; }
p > .md-image:only-child { display: inline-block; width: 100%; }
#write .MathJax_Display { margin: 0.8em 0px 0px; }
.md-math-block { width: 100%; }
.md-math-block:not(:empty)::after { display: none; }
.MathJax_ref { fill: currentcolor; }
[contenteditable="true"]:active, [contenteditable="true"]:focus, [contenteditable="false"]:active, [contenteditable="false"]:focus { outline: 0px; box-shadow: none; }
.md-task-list-item { position: relative; list-style-type: none; }
.task-list-item.md-task-list-item { padding-left: 0px; }
.md-task-list-item > input { position: absolute; top: 0px; left: 0px; margin-left: -1.2em; margin-top: calc(1em - 10px); border: none; }
.math { font-size: 1rem; }
.md-toc { min-height: 3.58rem; position: relative; font-size: 0.9rem; border-top-left-radius: 10px; border-top-right-radius: 10px; border-bottom-right-radius: 10px; border-bottom-left-radius: 10px; }
.md-toc-content { position: relative; margin-left: 0px; }
.md-toc-content::after, .md-toc::after { display: none; }
.md-toc-item { display: block; color: rgb(65, 131, 196); }
.md-toc-item a { text-decoration: none; }
.md-toc-inner:hover { text-decoration: underline; }
.md-toc-inner { display: inline-block; cursor: pointer; }
.md-toc-h1 .md-toc-inner { margin-left: 0px; font-weight: 700; }
.md-toc-h2 .md-toc-inner { margin-left: 2em; }
.md-toc-h3 .md-toc-inner { margin-left: 4em; }
.md-toc-h4 .md-toc-inner { margin-left: 6em; }
.md-toc-h5 .md-toc-inner { margin-left: 8em; }
.md-toc-h6 .md-toc-inner { margin-left: 10em; }
@media screen and (max-width: 48em) {
.md-toc-h3 .md-toc-inner { margin-left: 3.5em; }
.md-toc-h4 .md-toc-inner { margin-left: 5em; }
.md-toc-h5 .md-toc-inner { margin-left: 6.5em; }
.md-toc-h6 .md-toc-inner { margin-left: 8em; }
}
a.md-toc-inner { font-size: inherit; font-style: inherit; font-weight: inherit; line-height: inherit; }
.footnote-line a:not(.reversefootnote) { color: inherit; }
.md-attr { display: none; }
.md-fn-count::after { content: "."; }
code, pre, samp, tt { font-family: var(--monospace); }
kbd { margin: 0px 0.1em; padding: 0.1em 0.6em; font-size: 0.8em; color: rgb(36, 39, 41); background-color: rgb(255, 255, 255); border: 1px solid rgb(173, 179, 185); border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px; box-shadow: rgba(12, 13, 14, 0.2) 0px 1px 0px, rgb(255, 255, 255) 0px 0px 0px 2px inset; white-space: nowrap; vertical-align: middle; }
.md-comment { color: rgb(162, 127, 3); opacity: 0.8; font-family: var(--monospace); }
code { text-align: left; }
a.md-print-anchor { white-space: pre !important; border: none !important; display: inline-block !important; position: absolute !important; width: 1px !important; right: 0px !important; outline: 0px !important; text-shadow: initial !important; background-position: 0px 0px !important; }
.md-inline-math .MathJax_SVG .noError { display: none !important; }
.html-for-mac .inline-math-svg .MathJax_SVG { vertical-align: 0.2px; }
.md-fences-math .MathJax_SVG_Display, .md-math-block .MathJax_SVG_Display { text-align: center; margin: 0px; position: relative; text-indent: 0px; max-width: none; max-height: none; min-height: 0px; min-width: 100%; width: auto; overflow-y: visible; display: block !important; }
.MathJax_SVG_Display, .md-inline-math .MathJax_SVG_Display { width: auto; margin: inherit; display: inline-block !important; }
.MathJax_SVG .MJX-monospace { font-family: var(--monospace); }
.MathJax_SVG .MJX-sans-serif { font-family: sans-serif; }
.MathJax_SVG { display: inline; font-style: normal; font-weight: 400; line-height: normal; text-indent: 0px; text-align: left; text-transform: none; letter-spacing: normal; word-spacing: normal; word-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; zoom: 90%; }
#math-inline-preview-content { zoom: 1.1; }
.MathJax_SVG * { transition: none; }
.MathJax_SVG_Display svg { vertical-align: middle !important; margin-bottom: 0px !important; margin-top: 0px !important; }
.os-windows.monocolor-emoji .md-emoji { font-family: "Segoe UI Symbol", sans-serif; }
.md-diagram-panel > svg { max-width: 100%; }
[lang="flow"] svg, [lang="mermaid"] svg { max-width: 100%; height: auto; }
[lang="mermaid"] .node text { font-size: 1rem; }
table tr th { border-bottom-width: 0px; }
video { max-width: 100%; display: block; margin: 0px auto; }
iframe { max-width: 100%; width: 100%; border: none; }
.highlight td, .highlight tr { border: 0px; }
mark { background-color: rgb(255, 255, 0); color: rgb(0, 0, 0); }
.md-html-inline .md-plain, .md-html-inline strong, mark .md-inline-math, mark strong { color: inherit; }
.md-expand mark .md-meta { opacity: 0.3 !important; }
mark .md-meta { color: rgb(0, 0, 0); }
@media print {
.typora-export h1, .typora-export h2, .typora-export h3, .typora-export h4, .typora-export h5, .typora-export h6 { break-inside: avoid; }
}
.md-diagram-panel .messageText { stroke: none !important; }
.md-diagram-panel .start-state { fill: var(--node-fill); }
.md-diagram-panel .edgeLabel rect { opacity: 1 !important; }
.md-require-zoom-fix foreignObject { font-size: var(--mermaid-font-zoom); }
.md-fences.md-fences-math { font-size: 1em; }
.md-fences-math .MathJax_SVG_Display { margin-top: 8px; cursor: default; }
.md-fences-advanced:not(.md-focus) { padding: 0px; white-space: nowrap; border: 0px; }
.md-fences-advanced:not(.md-focus) { background-image: inherit; background-size: inherit; background-attachment: inherit; background-origin: inherit; background-clip: inherit; background-color: inherit; background-position: inherit; background-repeat: inherit; }
.typora-export-show-outline .typora-export-content { max-width: 1440px; margin: auto; display: flex; flex-direction: row; }
.typora-export-sidebar { width: 300px; font-size: 0.8rem; margin-top: 80px; margin-right: 18px; }
.typora-export-show-outline #write { --webkit-flex: 2; flex: 2 1 0%; }
.typora-export-sidebar .outline-content { position: fixed; top: 0px; max-height: 100%; overflow: hidden auto; padding-bottom: 30px; padding-top: 60px; width: 300px; }
@media screen and (max-width: 1024px) {
.typora-export-sidebar, .typora-export-sidebar .outline-content { width: 240px; }
}
@media screen and (max-width: 800px) {
.typora-export-sidebar { display: none; }
}
.outline-content li, .outline-content ul { margin-left: 0px; margin-right: 0px; padding-left: 0px; padding-right: 0px; list-style: none; }
.outline-content ul { margin-top: 0px; margin-bottom: 0px; }
.outline-content strong { font-weight: 400; }
.outline-expander { width: 1rem; height: 1.428571429rem; position: relative; display: table-cell; vertical-align: middle; cursor: pointer; padding-left: 4px; }
.outline-expander::before { content: ''; position: relative; font-family: Ionicons; display: inline-block; font-size: 8px; vertical-align: middle; }
.outline-item { padding-top: 3px; padding-bottom: 3px; cursor: pointer; }
.outline-expander:hover::before { content: ''; }
.outline-h1 > .outline-item { padding-left: 0px; }
.outline-h2 > .outline-item { padding-left: 1em; }
.outline-h3 > .outline-item { padding-left: 2em; }
.outline-h4 > .outline-item { padding-left: 3em; }
.outline-h5 > .outline-item { padding-left: 4em; }
.outline-h6 > .outline-item { padding-left: 5em; }
.outline-label { cursor: pointer; display: table-cell; vertical-align: middle; text-decoration: none; color: inherit; }
.outline-label:hover { text-decoration: underline; }
.outline-item:hover { border-color: rgb(245, 245, 245); background-color: var(--item-hover-bg-color); }
.outline-item:hover { margin-left: -28px; margin-right: -28px; border-left-width: 28px; border-left-style: solid; border-left-color: transparent; border-right-width: 28px; border-right-style: solid; border-right-color: transparent; }
.outline-item-single .outline-expander::before, .outline-item-single .outline-expander:hover::before { display: none; }
.outline-item-open > .outline-item > .outline-expander::before { content: ''; }
.outline-children { display: none; }
.info-panel-tab-wrapper { display: none; }
.outline-item-open > .outline-children { display: block; }
.typora-export .outline-item { padding-top: 1px; padding-bottom: 1px; }
.typora-export .outline-item:hover { margin-right: -8px; border-right-width: 8px; border-right-style: solid; border-right-color: transparent; }
.typora-export .outline-expander::before { content: "+"; font-family: inherit; top: -1px; }
.typora-export .outline-expander:hover::before, .typora-export .outline-item-open > .outline-item > .outline-expander::before { content: '−'; }
.typora-export-collapse-outline .outline-children { display: none; }
.typora-export-collapse-outline .outline-item-open > .outline-children, .typora-export-no-collapse-outline .outline-children { display: block; }
.typora-export-no-collapse-outline .outline-expander::before { content: "" !important; }
.typora-export-show-outline .outline-item-active > .outline-item .outline-label { font-weight: 700; }
.CodeMirror { height: auto; }
.CodeMirror.cm-s-inner { background-image: inherit; background-size: inherit; background-attachment: inherit; background-origin: inherit; background-clip: inherit; background-color: inherit; background-position: inherit; background-repeat: inherit; }
.CodeMirror-scroll { overflow: auto hidden; z-index: 3; }
.CodeMirror-gutter-filler, .CodeMirror-scrollbar-filler { background-color: rgb(255, 255, 255); }
.CodeMirror-gutters { border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); background-image: inherit; background-size: inherit; background-attachment: inherit; background-origin: inherit; background-clip: inherit; background-color: inherit; white-space: nowrap; background-position: inherit; background-repeat: inherit; }
.CodeMirror-linenumber { padding: 0px 3px 0px 5px; text-align: right; color: rgb(153, 153, 153); }
.cm-s-inner .cm-keyword { color: rgb(119, 0, 136); }
.cm-s-inner .cm-atom, .cm-s-inner.cm-atom { color: rgb(34, 17, 153); }
.cm-s-inner .cm-number { color: rgb(17, 102, 68); }
.cm-s-inner .cm-def { color: rgb(0, 0, 255); }
.cm-s-inner .cm-variable { color: rgb(0, 0, 0); }
.cm-s-inner .cm-variable-2 { color: rgb(0, 85, 170); }
.cm-s-inner .cm-variable-3 { color: rgb(0, 136, 85); }
.cm-s-inner .cm-string { color: rgb(170, 17, 17); }
.cm-s-inner .cm-property { color: rgb(0, 0, 0); }
.cm-s-inner .cm-operator { color: rgb(152, 26, 26); }
.cm-s-inner .cm-comment, .cm-s-inner.cm-comment { color: rgb(170, 85, 0); }
.cm-s-inner .cm-string-2 { color: rgb(255, 85, 0); }
.cm-s-inner .cm-meta { color: rgb(85, 85, 85); }
.cm-s-inner .cm-qualifier { color: rgb(85, 85, 85); }
.cm-s-inner .cm-builtin { color: rgb(51, 0, 170); }
.cm-s-inner .cm-bracket { color: rgb(153, 153, 119); }
.cm-s-inner .cm-tag { color: rgb(17, 119, 0); }
.cm-s-inner .cm-attribute { color: rgb(0, 0, 204); }
.cm-s-inner .cm-header, .cm-s-inner.cm-header { color: rgb(0, 0, 255); }
.cm-s-inner .cm-quote, .cm-s-inner.cm-quote { color: rgb(0, 153, 0); }
.cm-s-inner .cm-hr, .cm-s-inner.cm-hr { color: rgb(153, 153, 153); }
.cm-s-inner .cm-link, .cm-s-inner.cm-link { color: rgb(0, 0, 204); }
.cm-negative { color: rgb(221, 68, 68); }
.cm-positive { color: rgb(34, 153, 34); }
.cm-header, .cm-strong { font-weight: 700; }
.cm-del { text-decoration: line-through; }
.cm-em { font-style: italic; }
.cm-link { text-decoration: underline; }
.cm-error { color: red; }
.cm-invalidchar { color: red; }
.cm-constant { color: rgb(38, 139, 210); }
.cm-defined { color: rgb(181, 137, 0); }
div.CodeMirror span.CodeMirror-matchingbracket { color: rgb(0, 255, 0); }
div.CodeMirror span.CodeMirror-nonmatchingbracket { color: rgb(255, 34, 34); }
.cm-s-inner .CodeMirror-activeline-background { background-image: inherit; background-size: inherit; background-attachment: inherit; background-origin: inherit; background-clip: inherit; background-color: inherit; background-position: inherit; background-repeat: inherit; }
.CodeMirror { position: relative; overflow: hidden; }
.CodeMirror-scroll { height: 100%; outline: 0px; position: relative; box-sizing: content-box; background-image: inherit; background-size: inherit; background-attachment: inherit; background-origin: inherit; background-clip: inherit; background-color: inherit; background-position: inherit; background-repeat: inherit; }
.CodeMirror-sizer { position: relative; }
.CodeMirror-gutter-filler, .CodeMirror-hscrollbar, .CodeMirror-scrollbar-filler, .CodeMirror-vscrollbar { position: absolute; z-index: 6; display: none; }
.CodeMirror-vscrollbar { right: 0px; top: 0px; overflow: hidden; }
.CodeMirror-hscrollbar { bottom: 0px; left: 0px; overflow: hidden; }
.CodeMirror-scrollbar-filler { right: 0px; bottom: 0px; }
.CodeMirror-gutter-filler { left: 0px; bottom: 0px; }
.CodeMirror-gutters { position: absolute; left: 0px; top: 0px; padding-bottom: 30px; z-index: 3; }
.CodeMirror-gutter { white-space: normal; height: 100%; box-sizing: content-box; padding-bottom: 30px; margin-bottom: -32px; display: inline-block; }
.CodeMirror-gutter-wrapper { position: absolute; z-index: 4; border: none !important; background-position: 0px 0px !important; }
.CodeMirror-gutter-background { position: absolute; top: 0px; bottom: 0px; z-index: 4; }
.CodeMirror-gutter-elt { position: absolute; cursor: default; z-index: 4; }
.CodeMirror-lines { cursor: text; }
.CodeMirror pre { border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; border-width: 0px; font-family: inherit; font-size: inherit; margin: 0px; white-space: pre; word-wrap: normal; color: inherit; z-index: 2; position: relative; overflow: visible; background-position: 0px 0px; }
.CodeMirror-wrap pre { word-wrap: break-word; white-space: pre-wrap; word-break: normal; }
.CodeMirror-code pre { border-right-width: 30px; border-right-style: solid; border-right-color: transparent; width: fit-content; }
.CodeMirror-wrap .CodeMirror-code pre { border-right-style: none; width: auto; }
.CodeMirror-linebackground { position: absolute; inset: 0px; z-index: 0; }
.CodeMirror-linewidget { position: relative; z-index: 2; overflow: auto; }
.CodeMirror-wrap .CodeMirror-scroll { overflow-x: hidden; }
.CodeMirror-measure { position: absolute; width: 100%; height: 0px; overflow: hidden; visibility: hidden; }
.CodeMirror-measure pre { position: static; }
.CodeMirror div.CodeMirror-cursor { position: absolute; visibility: hidden; border-right-style: none; width: 0px; }
.CodeMirror div.CodeMirror-cursor { visibility: hidden; }
.CodeMirror-focused div.CodeMirror-cursor { visibility: inherit; }
.cm-searching { background-color: rgba(255, 255, 0, 0.4); }
span.cm-underlined { text-decoration: underline; }
span.cm-strikethrough { text-decoration: line-through; }
.cm-tw-syntaxerror { color: rgb(255, 255, 255); background-color: rgb(153, 0, 0); }
.cm-tw-deleted { text-decoration: line-through; }
.cm-tw-header5 { font-weight: 700; }
.cm-tw-listitem:first-child { padding-left: 10px; }
.cm-tw-box { border-style: solid; border-right-width: 1px; border-bottom-width: 1px; border-left-width: 1px; border-color: inherit; border-top-width: 0px !important; }
.cm-tw-underline { text-decoration: underline; }
@media print {
.CodeMirror div.CodeMirror-cursor { visibility: hidden; }
}
:root {
--side-bar-bg-color: #fafafa;
--control-text-color: #777;
}
@include-when-export url(https://fonts.loli.net/css?family=Open+Sans:400italic,700italic,700,400&subset=latin,latin-ext);
/* open-sans-regular - latin-ext_latin */
/* open-sans-italic - latin-ext_latin */
/* open-sans-700 - latin-ext_latin */
/* open-sans-700italic - latin-ext_latin */
html {
font-size: 16px;
}
body {
font-family: "Open Sans","Clear Sans", "Helvetica Neue", Helvetica, Arial, sans-serif;
color: rgb(51, 51, 51);
line-height: 1.6;
}
#write {
max-width: 860px;
margin: 0 auto;
padding: 30px;
padding-bottom: 100px;
}
@media only screen and (min-width: 1400px) {
#write {
max-width: 1024px;
}
}
@media only screen and (min-width: 1800px) {
#write {
max-width: 1200px;
}
}
#write > ul:first-child,
#write > ol:first-child{
margin-top: 30px;
}
a {
color: #4183C4;
}
h1,
h2,
h3,
h4,
h5,
h6 {
position: relative;
margin-top: 1rem;
margin-bottom: 1rem;
font-weight: bold;
line-height: 1.4;
cursor: text;
}
h1:hover a.anchor,
h2:hover a.anchor,
h3:hover a.anchor,
h4:hover a.anchor,
h5:hover a.anchor,
h6:hover a.anchor {
text-decoration: none;
}
h1 tt,
h1 code {
font-size: inherit;
}
h2 tt,
h2 code {
font-size: inherit;
}
h3 tt,
h3 code {
font-size: inherit;
}
h4 tt,
h4 code {
font-size: inherit;
}
h5 tt,
h5 code {
font-size: inherit;
}
h6 tt,
h6 code {
font-size: inherit;
}
h1 {
font-size: 2.25em;
line-height: 1.2;
border-bottom: 1px solid #eee;
}
h2 {
font-size: 1.75em;
line-height: 1.225;
border-bottom: 1px solid #eee;
}
/*@media print {
.typora-export h1,
.typora-export h2 {
border-bottom: none;
padding-bottom: initial;
}
.typora-export h1::after,
.typora-export h2::after {
content: "";
display: block;
height: 100px;
margin-top: -96px;
border-top: 1px solid #eee;
}
}*/
h3 {
font-size: 1.5em;
line-height: 1.43;
}
h4 {
font-size: 1.25em;
}
h5 {
font-size: 1em;
}
h6 {
font-size: 1em;
color: #777;
}
p,
blockquote,
ul,
ol,
dl,
table{
margin: 0.8em 0;
}
li>ol,
li>ul {
margin: 0 0;
}
hr {
height: 2px;
padding: 0;
margin: 16px 0;
background-color: #e7e7e7;
border: 0 none;
overflow: hidden;
box-sizing: content-box;
}
li p.first {
display: inline-block;
}
ul,
ol {
padding-left: 30px;
}
ul:first-child,
ol:first-child {
margin-top: 0;
}
ul:last-child,
ol:last-child {
margin-bottom: 0;
}
blockquote {
border-left: 4px solid #dfe2e5;
padding: 0 15px;
color: #777777;
}
blockquote blockquote {
padding-right: 0;
}
table {
padding: 0;
word-break: initial;
}
table tr {
border: 1px solid #dfe2e5;
margin: 0;
padding: 0;
}
table tr:nth-child(2n),
thead {
background-color: #f8f8f8;
}
table th {
font-weight: bold;
border: 1px solid #dfe2e5;
border-bottom: 0;
margin: 0;
padding: 6px 13px;
}
table td {
border: 1px solid #dfe2e5;
margin: 0;
padding: 6px 13px;
}
table th:first-child,
table td:first-child {
margin-top: 0;
}
table th:last-child,
table td:last-child {
margin-bottom: 0;
}
.CodeMirror-lines {
padding-left: 4px;
}
.code-tooltip {
box-shadow: 0 1px 1px 0 rgba(0,28,36,.3);
border-top: 1px solid #eef2f2;
}
.md-fences,
code,
tt {
border: 1px solid #e7eaed;
background-color: #f8f8f8;
border-radius: 3px;
padding: 0;
padding: 2px 4px 0px 4px;
font-size: 0.9em;
}
code {
background-color: #f3f4f4;
padding: 0 2px 0 2px;
}
.md-fences {
margin-bottom: 15px;
margin-top: 15px;
padding-top: 8px;
padding-bottom: 6px;
}
.md-task-list-item > input {
margin-left: -1.3em;
}
@media print {
html {
font-size: 13px;
}
table,
pre {
page-break-inside: avoid;
}
pre {
word-wrap: break-word;
}
}
.md-fences {
background-color: #f8f8f8;
}
#write pre.md-meta-block {
padding: 1rem;
font-size: 85%;
line-height: 1.45;
background-color: #f7f7f7;
border: 0;
border-radius: 3px;
color: #777777;
margin-top: 0 !important;
}
.mathjax-block>.code-tooltip {
bottom: .375rem;
}
.md-mathjax-midline {
background: #fafafa;
}
#write>h3.md-focus:before{
left: -1.5625rem;
top: .375rem;
}
#write>h4.md-focus:before{
left: -1.5625rem;
top: .285714286rem;
}
#write>h5.md-focus:before{
left: -1.5625rem;
top: .285714286rem;
}
#write>h6.md-focus:before{
left: -1.5625rem;
top: .285714286rem;
}
.md-image>.md-meta {
/*border: 1px solid #ddd;*/
border-radius: 3px;
padding: 2px 0px 0px 4px;
font-size: 0.9em;
color: inherit;
}
.md-tag {
color: #a7a7a7;
opacity: 1;
}
.md-toc {
margin-top:20px;
padding-bottom:20px;
}
.sidebar-tabs {
border-bottom: none;
}
#typora-quick-open {
border: 1px solid #ddd;
background-color: #f8f8f8;
}
#typora-quick-open-item {
background-color: #FAFAFA;
border-color: #FEFEFE #e5e5e5 #e5e5e5 #eee;
border-style: solid;
border-width: 1px;
}
/** focus mode */
.on-focus-mode blockquote {
border-left-color: rgba(85, 85, 85, 0.12);
}
header, .context-menu, .megamenu-content, footer{
font-family: "Segoe UI", "Arial", sans-serif;
}
.file-node-content:hover .file-node-icon,
.file-node-content:hover .file-node-open-state{
visibility: visible;
}
.mac-seamless-mode #typora-sidebar {
background-color: #fafafa;
background-color: var(--side-bar-bg-color);
}
.md-lang {
color: #b4654d;
}
/*.html-for-mac {
--item-hover-bg-color: #E6F0FE;
}*/
#md-notification .btn {
border: 0;
}
.dropdown-menu .divider {
border-color: #e5e5e5;
opacity: 0.4;
}
.ty-preferences .window-content {
background-color: #fafafa;
}
.ty-preferences .nav-group-item.active {
color: white;
background: #999;
}
.menu-item-container a.menu-style-btn {
background-color: #f5f8fa;
background-image: linear-gradient( 180deg , hsla(0, 0%, 100%, 0.8), hsla(0, 0%, 100%, 0));
}
:root {--mermaid-font-zoom:1em ;} @media print { @page {margin: 0 0 0 0;} body.typora-export {padding-left: 0; padding-right: 0;} #write {padding:0;}}
目录技术概要:数据弹性和镜像数据弹性(Data Resiliency):InterSystems IRIS 提供什么数据弹性(Data Resiliency):InterSystems IRIS 如何提供写入映像日志(Write Image Journaling):防止物理数据损坏和丢失 日志(Journaling):防止逻辑数据损坏和丢失 镜像(Mirroring):高可用性和灾备解决方案 镜像虚拟化平台使用InterSystems IRIS镜像一个数据库:试一试了解有关 InterSystems 数据弹性的更多信息技术概要:数据弹性和镜像本技术概要(First Look)将向您介绍InterSystems IRIS®数据平台的数据弹性(data resiliency)功能。数据弹性包括三个目标------崩溃恢复、高可用性和灾备------这些都是通过 InterSystems IRIS 的几个功能实现的。InterSystems IRIS 的主要功能之一是能够利用逻辑数据复制提供对数据的连续和不间断访问。数据可以同步复制,以允许在各种故障情况下自动故障转移而不会丢失数据,无论是计划内的(例如软件升级)还是计划外的(例如硬件故障)。同步复制数据需要两个节点之间低延迟,因此并不总是适用于跨国家传输数据的灾备(DR)场景。对于这些场景,InterSystems IRIS 提供了内置的异步数据复制。InterSystems IRIS 的镜像功能提供了高可用性。在了解了 InterSystems IRIS 数据弹性后,您将创建一个镜像(mirror),在主成员上进行数据更改,并自动同步复制到备份成员上,然后关闭主成员,使镜像故障转移到备份上。这些活动只使用默认设置,因此您可以熟悉这些功能的基本原理。有关完整的文档,请参见 InterSystems IRIS Data Integrity Guide(《InterSystems IRIS 数据完整性指南》)。[]{#1_Data_Resiliency:_What_InterSystems_IRI .anchor}要浏览所有的技术概要(First Looks),包括那些可以在免费的云实例或 web 实例上执行的技术概要(First Looks),请参见InterSystems 技术概要。数据弹性(Data Resiliency):InterSystems IRIS 提供什么数据弹性涵盖多个主题,但它们都围绕着一个原则:一旦数据被记录在数据平台上,无论发生什么,它都是可以访问的。为了实现这一目标,有几个不同的地方需要解决:即使在发生错误或电源故障的情况下,也能保证数据的有效性从 InterSystems IRIS 服务器的本地故障中进行崩溃恢复,无论是物理故障还是软件相关的故障。防止全站点灾难(断电、网络问题等。)为了满足这些要求,InterSystems IRIS 提供了:结构化数据库完整性(磁盘上数据库块的内容)和防止内部完整性故障(数据库中表示的数据)通过事务处理、锁定和自动回滚实现逻辑数据库完整性内置的高可用性解决方案,具有自动故障转移功能逻辑数据复制,最大限度地降低了结转物理损坏的风险,并且不依赖共享资源计划内和计划外停机的解决方案通过地理上分散的灾难恢复配置带来业务连续性优势InterSystems IRIS 数据弹性全天候保护您生产系统上的数据。数据弹性:InterSystems IRIS 如何提供数据弹性(Data Resiliency):InterSystems IRIS 如何提供系统停机的成本从数千美元到数百万美元不等,具体取决于停机的类型和时间长度以及受影响的系统类型。从停机中快速恢复固然很重要,但恢复数据并确保您的数据不会丢失和损坏的能力也很重要。InterSystems IRIS 写入映像日志技术(write image journaling technology)提供结构化数据库的完整性(磁盘上数据库块的内容),并防止由于系统崩溃而导致的内部完整性故障(数据库中表示的数据)。InterSystems IRIS 备份和日志系统提供物理完整性故障的快速恢复。数据弹性通过事务处理[]{#2.1_Write_Image_Journaling:_Protection_A .anchor}、锁定和自动回滚确保逻辑数据库完整性。除了日志提供的功能外,InterSystems IRIS 还允许您对数据库进行镜像,以提供快速、高效的数据复制和灾难恢复。写入映像日志(Write Image Journaling):防止物理数据损坏和丢失 任何突然的、意外的磁盘或计算机操作中断都可能在第一个数据块(block)被写入后但在最后一个数据块(block)被更新前停止对多个数据库块的更新。其后果可能与数据库完全不可用一样严重,所有数据都无法通过正常方式恢复。 InterSystems IRIS 写入映像日记技术(Write image journaling,WIJ)可以防止这种数据损坏。它可以防止不完整的更新导致不一致的数据库结构。写入映像日志(WIJ)通过使用两阶段(two-phase)方法来保护数据库更新。InterSystems IRIS 实例首先将更新从内存写入过渡日志,即 IRIS.WIJ 文件,然后再写入数据库。如果系统在第一阶段崩溃,则删除更新而不对数据库进行任何更改;如果崩溃发生在第二阶段,您可以在恢复时重新应用写入映像日志(WIJ)的更新,确保对数据库进行所有更新。写入守护进程(The write daemon)在 InterSystems IRIS 启动时创建写入映像日志(WIJ)文件,并在将数据库更新写入 InterSystems IRIS 数据库之前记录 WIJ 中的数据库更新。一旦它输入对 WIJ 的所有更新,它就在文件中设置一个标志,第二阶段开始,写入守护进程将 WIJ 中记录的同一组块写入磁盘上的数据库中。当第二阶段完成时,写入守护进程在 WIJ 中设置一个标志,表示它已被删除。当 InterSystems IRIS 启动时,它会自动检查 WIJ,并在检测到发生异常关机时运行恢复程序。当该程序成功完成时,将恢复数据库的内部完整性。InterSystems IRIS 还在关机后运行 WIJ 恢复作为安全预防措施,以确保数据可以安全备份。根据 WIJ 在两阶段(two-phase)写入协议进程中的位置,恢复执行以下操作:如果崩溃发生在对 WIJ 的最后一次更新完成之后,但在对数据库的相应更新完成之前,那么 WIJ 将被恢复。如果崩溃发生在最后一次 WIJ 更新被持久地写入数据库之后,则会在最近的 WIJ 更新和受影响的数据库之间进行块比较。日志(Journaling):防止逻辑数据损坏和丢失 日志(Journaling)是一个可以在每个数据库基础上启用的功能,它提供所有数据库修改的完整记录。在发生崩溃的情况下,可以在恢复备份之后,从日志中重新应用自最近备份以来所做的更新,以使数据库恢复到发生崩溃的点。InterSystems IRIS 恢复过程通过使用"前滚"的方法提供最大程度的保护。如果发生系统崩溃,恢复机制将完成正在进行的更新。它还保护了更新的顺序;如果恢复后数据库中存在一个更新,那么之前的所有更新也都存在。这可以保护数据弹性:InterSystems IRIS 如何提供增量备份文件结构以及数据库。您可以在崩溃恢复后运行有效的增量备份。日志是数据弹性的第三个功能:镜像的基础。镜像(Mirroring):高可用性和灾备解决方案 InterSystems IRIS 镜像(Mirroring)属于系统可用性策略中的自动故障转移类别。镜像为数据库的可用性提供了全面、可靠和强健的企业解决方案。依赖共享资源(如共享磁盘)的传统可用性解决方案往往容易受到与该共享资源有关的单点故障的影响。镜像通过在主镜像成员和备份镜像成员上维护独立的资源来降低这种风险。此外,通过使用逻辑数据复制,镜像避免了与物理复制技术(如基于 SAN 的复制)相关的风险,包括无序更新和结转损坏。InterSystems IRIS 为高可用性镜像提供了两个选项:镜像(Mirroring)和虚拟化(Virtualization)。镜像具有自动故障转移功能的 InterSystems IRIS 镜像依赖于完全独立系统之间的逻辑数据复制。这避免了在为多个系统使用共享存储时出现单点故障的风险。它还确保在所有故障场景(系统、存储和网络)中,生产系统可以立即将故障转移到备用 InterSystems IRIS 实例。在 InterSystems IRIS 镜像中,一个被称为主故障转移成员的 InterSystems IRIS 实例,提供对生产数据库的访问。另一台主机上的另一个实例(称之为备份故障转移成员),与主服务器同步通信,检索主服务器的日志记录,确认收到日志记录,并将它们应用到同一数据库的自己的副本上。通过这种方式,主服务器和备份服务器总是知道备份服务器是否拥有来自主服务器的最新日志文件,因此可以精确地将其数据库与主服务器上的数据库进行同步。InterSystems IRIS 镜像的另一大功能是允许配置一个特殊的异步成员,它可以从整个企业的多个镜像中接收更新。您可以为单个镜像的灾备配置一个异步成员,这允许它在需要时无缝地替代一个故障转移成员的位置。一个镜像最多可以包括 16 个成员,这使您可以配置多个地理上分散的 灾备(DR) 异步成员。这种模式为分布式数据复制提供了一个强健的框架,从而确保业务连续性有利于组织。另一个好处是,使用异步成员的镜像允许单个系统充当全面的企业数据仓库。这为您提供了企业范围内的数据挖掘和业务智能。虚拟化平台虚拟化平台通常提供 高可用(HA) 功能,这些功能通常监视客户操作系统和运行它的硬件的状态。在虚拟化环境中使用镜像,构成镜像的 InterSystems IRIS 实例安装在虚拟主机上,创造了一个混合的高可用性解决方案,结合了镜像和虚拟化的优势。虽然镜像通过自动故障转移对计划内或计划外的故障提供即时响应,但虚拟化 HA 软件在计划外的机器或 OS 故障后自动重新启动托管镜像成员的虚拟机。这允许失败的成员快速重新加入镜像,以充当备份(或在必要时作为主要成员接管)。在任何一个发生故障时,虚拟化平台都会根据需要在备用硬件上自动重新启动故障的虚拟机。当 InterSystems IRIS 实例重新启动时,它会自动执行正常的启动恢复,保持结构和逻辑完整性,就像您在物理服务器上重新启动 InterSystems IRIS 一样。使用InterSystems IRIS镜像一个数据库:试一试现在您已经对 InterSystems IRIS 数据弹性及其提供的功能有了一些背景知识,让我们通过镜像来了解其中的一部分。使用 InterSystems IRIS 设置镜像环境很容易。您可以使用自动提供、部署和配置镜像的 InterSystems 云管理器(InterSystems Cloud Manager,ICM),也可以使用管理门户(Management Portal)进行手动配置。本文档介绍如何使用 ICM 部署镜像。(关于使用管理门户[Management Portal]使用两个已安装的 InterSystems IRIS 实例创建镜像的步骤,请参见 High Availability Guide[《高可用性指南》]的 "Mirroring[镜像]"一章中的 Creating a Mirror[创建镜像])。在这种情况下,您将在亚马逊网络服务(Amazon Web Services)公共云中部署一对镜像的 InterSystems IRIS 实例。要做到这一点,请按照《技术概要:InterSystems 云管理器》中 Try It! Deploy InterSystems IRIS in the Cloud with ICM(试一试!使用 ICM 在云中部署 InterSystems IRIS)的 Customize the Sample Configuration Files(自定义示例配置文件)一节中的步骤,进行以下修改:在 defaults.json 文件中,添加"Mirror": "True"。自定义 definitions.json 文件,添加一个 AR 节点定义,指定 arbiter 映像。[ { "Role": "DATA", "Count": "2", "LicenseKey": "ubuntu-sharding-iris.key" }, { "Role": "AR", "Count": "1", "StartCount": "3", "DockerImage": "intersystems/arbiter:stable" }]DockerImage 属性必须是 AR 节点定义的一部分,因为 AR 节点使用不同于 InterSystems IRIS 节点(如 DATA)的 InterSystems 映像(image)。您必须确保 arbiter 映像(image)在本地可用;有关此操作的信息,请参见《技术概要:InterSystems 云管理器》中的 Identify Docker Repository and Credentials(识别 Docker 存储库和凭证)。一旦您定制了配置文件,包括这些变化,就继续执行程序。当您完成了"部署 InterSystems IRIS"步骤(icm run 命令),并且镜像已经部署在云中,继续使用 ICM 命令行来尝试镜像:在主故障转移成员上设置 global,并验证它在备份故障转移成员上也被设置了。触发计划的从主服务器到备份服务器的故障转移。要做到这一点,请使用以下程序:在 ICM 命令行上,通过输入 icm inventory 命令,查看您的镜像成员的名称和镜像角色,其中列出了您已经配置的云主机节点。ICM 提供的节点被命名为 Label-Role-Tag-NNNN;其中 Role 是 ICM 节点类型,在本例中是 DATA,其他部分由您赋值。镜像成员用 +(加号)表示初始主节点,用 -(减号)表示初始备份。本程序其余部分的示例假设您把 label 字段设置为 Acme,把 tag 字段设置为 TEST,从而产生如下所示的 icm inventory 输出:$ icm inventoryMachine IP Address DNS Name Region ZoneAcme-DATA-TEST-0001+ 00.53.183.209 ec2-00-53-183-209.us-west-1.compute.amazonaws.com us-west-1 cAcme-DATA-TEST-0002- 00.53.183.185 ec2-00-53-183-185.us-west-1.compute.amazonaws.com us-west-1 c使用InterSystems IRIS镜像一个数据库:试一试注意: 节点编号和镜像角色之间没有关系。 + 和 - 符号仅表示初始镜像赋值;对于实时镜像状态,请使用 icm ps 命令。通过输入命令在主镜像成员上打开 InterSystems 终端(Terminal):$ icm session -interactive -machine Acme-DATA-TEST-0001当终端(Terminal)窗口打开时,您就处于 DB 命名空间,它被映射到镜像数据库 DB;ICM 默认创建了这两个数据库。输入以下命令在 DB 数据库中创建 global(globals 在 InterSystems IRIS 数据库中存储数据):DB> Set \^myfirstglobal="congratulations"输入以下命令来显示 global 的值:DB> Write \^myfirstglobal congratulations使用以下命令为备份故障转移成员打开终端(Terminal)窗口:$ icm session -interactive -machine Acme-DATA-TEST-0002输入相同的 Write 命令;global 已经存在,并且其值是您在主服务器上设置的。数据被自动同步地镜像到备份中的 DB 数据库。DB> Write \^myfirstglobal congratulations备份中的镜像数据库是只读的;如果您试图改变 global 的值,您会得到一个错误。DB> Set \^myfirstglobal="what next?"<PROTECT>返回到 ICM 命令行,使用以下命令关闭并重新启动其容器内的主要 InterSystems IRIS 实例(ICM 默认将其命名为 IRIS):$ icm exec -command "iris stop IRIS quietly restart" -machine Acme-DATA-TEST-0001注意: -quietly 参数防止 iris stop 命令提示发行者,这将导致 ICM 等待直到超时。另外,您可以交互式地执行命令,如下所示,从而允许您响应提示:$ icm exec -command "iris stop IRIS restart" -interactive -machine Acme-DATA-TEST-0001等待几秒钟,然后返回 Acme-DATA-TEST-0002 上的终端(Terminal)窗口。当主服务器由于计划或计划外的故障而不可用时,镜像将自动故障转移到备份服务器,备份服务器将成为新的主服务器。因此,Acme-DATA-TEST-0002 已经成为主服务器,您现在可以更改 global 的值了。DB> Set \^myfirstglobal="what next?"DB> Write \^myfirstglobal what next?使用 icm ps 命令显示新的镜像角色:$ icm ps了解有关 InterSystems 数据弹性的更多信息为以前的主服务器 Acme-DATA-TEST-0001 打开一个新的终端(Terminal)窗口,重新启动时发现 Acme-DATA-TEST-0002 现在是主服务器,因此成为新的备份。因此,global 的值已经被更新为您在新的主节点上设置的值,您无法更改它。$ icm session -interactive -machine Acme-DATA-TEST-0001 DB> Write \^myfirstglobalwhat next?DB> Set \^myfirstglobal="another First Look!"<PROTECT>备份镜像成员随时准备接管主成员,以保持数据库可用,并保护您的数据不被损坏和丢失。当您完成镜像体验后,请务必返回《技术概要:InterSystems 云管理器》中的 Unprovision the Infrastructure(取消配置基础设施),并根据取消配置您的云节点的程序进行操作。因为 AWS 和其他公共云[]{#4_Learn_More_About_InterSystems_Data_Res .anchor}平台实例会不断产生费用,所以在使用完基础设施后立即取消配置是很重要的。了解有关 InterSystems 数据弹性的更多信息要了解有关 InterSystems IRIS 数据弹性和 ICM 的更多信息,请参见进一步阅读:High Availability Guide(《高可用性指南》)Data Integrity Guide(《数据完整性指南》)InterSystems Cloud Manager Guide(《InterSystems 云管理器指南》)What is InterSystems Cloud Manager?(《什么是 InterSystems 云管理器?》)(视频)The ICM Experience:Pat and Tracy (《ICM 体验:Pat 和 Tracy》) (视频)InterSystems in the Cloud Experience(《云体验中的 InterSystems》) (在线体验)