Fix performance of home feed regeneration (#12084)

Fetching statuses from all followed accounts at once takes too long
within Postgres. Fetching them one by one and merging in Ruby
could be a lot less resource-intensive

Because the query for dynamically fetching the home timeline is so
heavy, we can no longer offer it when the home timeline is missing

7 files changed, 49 insertions, 44 deletions

diff --git a/app/javascript/mastodon/actions/timelines.js b/app/javascript/mastodon/actions/timelines.js
index 7eeba2aa7..bc2ac5e82 100644
--- a/app/javascript/mastodon/actions/timelines.js
+++ b/app/javascript/mastodon/actions/timelines.js
@@ -97,7 +97,7 @@ export function expandTimeline(timelineId, path, params = {}, done = noOp) {
     api(getState).get(path, { params }).then(response => {
       const next = getLinks(response).refs.find(link => link.rel === 'next');
       dispatch(importFetchedStatuses(response.data));
-      dispatch(expandTimelineSuccess(timelineId, response.data, next ? next.uri : null, response.code === 206, isLoadingRecent, isLoadingMore, isLoadingRecent && preferPendingItems));
+      dispatch(expandTimelineSuccess(timelineId, response.data, next ? next.uri : null, response.status === 206, isLoadingRecent, isLoadingMore, isLoadingRecent && preferPendingItems));
       done();
     }).catch(error => {
       dispatch(expandTimelineFail(timelineId, error, isLoadingMore));
diff --git a/app/javascript/mastodon/components/missing_indicator.js b/app/javascript/mastodon/components/missing_indicator.js
index 70d8c3b98..7b0101bab 100644
--- a/app/javascript/mastodon/components/missing_indicator.js
+++ b/app/javascript/mastodon/components/missing_indicator.js
@@ -1,17 +1,24 @@
 import React from 'react';
+import PropTypes from 'prop-types';
 import { FormattedMessage } from 'react-intl';
+import illustration from 'mastodon/../images/elephant_ui_disappointed.svg';
+import classNames from 'classnames';
 
-const MissingIndicator = () => (
-  <div className='regeneration-indicator missing-indicator'>
-    <div>
-      <div className='regeneration-indicator__figure' />
+const MissingIndicator = ({ fullPage }) => (
+  <div className={classNames('regeneration-indicator', { 'regeneration-indicator--without-header': fullPage })}>
+    <div className='regeneration-indicator__figure'>
+      <img src={illustration} alt='' />
+    </div>
 
-      <div className='regeneration-indicator__label'>
-        <FormattedMessage id='missing_indicator.label' tagName='strong' defaultMessage='Not found' />
-        <FormattedMessage id='missing_indicator.sublabel' defaultMessage='This resource could not be found' />
-      </div>
+    <div className='regeneration-indicator__label'>
+      <FormattedMessage id='missing_indicator.label' tagName='strong' defaultMessage='Not found' />
+      <FormattedMessage id='missing_indicator.sublabel' defaultMessage='This resource could not be found' />
     </div>
   </div>
 );
 
+MissingIndicator.propTypes = {
+  fullPage: PropTypes.bool,
+};
+
 export default MissingIndicator;
diff --git a/app/javascript/mastodon/components/regeneration_indicator.js b/app/javascript/mastodon/components/regeneration_indicator.js
new file mode 100644
index 000000000..faf88c6b5
--- /dev/null
+++ b/app/javascript/mastodon/components/regeneration_indicator.js
@@ -0,0 +1,18 @@
+import React from 'react';
+import { FormattedMessage } from 'react-intl';
+import illustration from 'mastodon/../images/elephant_ui_working.svg';
+
+const MissingIndicator = () => (
+  <div className='regeneration-indicator'>
+    <div className='regeneration-indicator__figure'>
+      <img src={illustration} alt='' />
+    </div>
+
+    <div className='regeneration-indicator__label'>
+      <FormattedMessage id='regeneration_indicator.label' tagName='strong' defaultMessage='Loading&hellip;' />
+      <FormattedMessage id='regeneration_indicator.sublabel' defaultMessage='Your home feed is being prepared!' />
+    </div>
+  </div>
+);
+
+export default MissingIndicator;
diff --git a/app/javascript/mastodon/components/status_list.js b/app/javascript/mastodon/components/status_list.js
index 745e6422d..e1b370c91 100644
--- a/app/javascript/mastodon/components/status_list.js
+++ b/app/javascript/mastodon/components/status_list.js
@@ -1,12 +1,12 @@
 import { debounce } from 'lodash';
 import React from 'react';
-import { FormattedMessage } from 'react-intl';
 import ImmutablePropTypes from 'react-immutable-proptypes';
 import PropTypes from 'prop-types';
 import StatusContainer from '../containers/status_container';
 import ImmutablePureComponent from 'react-immutable-pure-component';
 import LoadGap from './load_gap';
 import ScrollableList from './scrollable_list';
+import RegenerationIndicator from 'mastodon/components/regeneration_indicator';
 
 export default class StatusList extends ImmutablePureComponent {
 
@@ -81,18 +81,7 @@ export default class StatusList extends ImmutablePureComponent {
     const { isLoading, isPartial } = other;
 
     if (isPartial) {
-      return (
-        <div className='regeneration-indicator'>
-          <div>
-            <div className='regeneration-indicator__figure' />
-
-            <div className='regeneration-indicator__label'>
-              <FormattedMessage id='regeneration_indicator.label' tagName='strong' defaultMessage='Loading&hellip;' />
-              <FormattedMessage id='regeneration_indicator.sublabel' defaultMessage='Your home feed is being prepared!' />
-            </div>
-          </div>
-        </div>
-      );
+      return <RegenerationIndicator />;
     }
 
     let scrollableContent = (isLoading || statusIds.size > 0) ? (
diff --git a/app/javascript/mastodon/features/generic_not_found/index.js b/app/javascript/mastodon/features/generic_not_found/index.js
index 0290be47f..41cd61a5f 100644
--- a/app/javascript/mastodon/features/generic_not_found/index.js
+++ b/app/javascript/mastodon/features/generic_not_found/index.js
@@ -4,7 +4,7 @@ import MissingIndicator from '../../components/missing_indicator';
 
 const GenericNotFound = () => (
   <Column>
-    <MissingIndicator />
+    <MissingIndicator fullPage />
   </Column>
 );
 
diff --git a/app/javascript/styles/mastodon/components.scss b/app/javascript/styles/mastodon/components.scss
index a6675b8ed..d9182ade9 100644
--- a/app/javascript/styles/mastodon/components.scss
+++ b/app/javascript/styles/mastodon/components.scss
@@ -3127,37 +3127,27 @@ a.status-card.compact:hover {
   cursor: default;
   display: flex;
   flex: 1 1 auto;
+  flex-direction: column;
   align-items: center;
   justify-content: center;
   padding: 20px;
 
-  & > div {
-    width: 100%;
-    background: transparent;
-    padding-top: 0;
-  }
-
   &__figure {
-    background: url('../images/elephant_ui_working.svg') no-repeat center 0;
-    width: 100%;
-    height: 160px;
-    background-size: contain;
-    position: absolute;
-    top: 50%;
-    left: 50%;
-    transform: translate(-50%, -50%);
+    &,
+    img {
+      display: block;
+      width: auto;
+      height: 160px;
+      margin: 0;
+    }
   }
 
-  &.missing-indicator {
+  &--without-header {
     padding-top: 20px + 48px;
-
-    .regeneration-indicator__figure {
-      background-image: url('../images/elephant_ui_disappointed.svg');
-    }
   }
 
   &__label {
-    margin-top: 200px;
+    margin-top: 30px;
 
     strong {
       display: block;
diff --git a/app/javascript/styles/mastodon/introduction.scss b/app/javascript/styles/mastodon/introduction.scss
index 222d8f60e..b44ae7306 100644
--- a/app/javascript/styles/mastodon/introduction.scss
+++ b/app/javascript/styles/mastodon/introduction.scss
@@ -3,9 +3,10 @@
   flex-direction: column;
   justify-content: center;
   align-items: center;
+  height: 100vh;
+  background: $ui-base-color;
 
   @media screen and (max-width: 920px) {
-    background: darken($ui-base-color, 8%);
     display: block !important;
   }