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perf(dashboard): avoid full note reads when building excerpts #1886

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perf(dashboard): avoid full note reads when building excerpts #1886

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db6ceec
perf(note): stream excerpt instead of reading full note
joshtrichards Jun 4, 2026
957ec08
perf: use pre-compiled string literal for BOM stripping
joshtrichards Jun 4, 2026
9a9f8b1
chore(Note): fixup
joshtrichards Jun 4, 2026
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50 changes: 44 additions & 6 deletions lib/Service/Note.php
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Original file line number Diff line number Diff line change
Expand Up @@ -56,26 +56,64 @@ public function getContent() : string {
);
$content = mb_convert_encoding($content, 'UTF-8');
}
$content = str_replace([ pack('H*', 'FEFF'), pack('H*', 'FFEF'), pack('H*', 'EFBBBF') ], '', $content);

// Strip Byte Order Marks (BOM) for UTF-8, UTF-16 BE, and UTF-16 LE
$content = str_replace(["\xEF\xBB\xBF", "\xFE\xFF", "\xFF\xFE"], '', $content);

return $content;
}

public function getExcerpt(int $maxlen = 100) : string {
$excerpt = trim($this->noteUtil->stripMarkdown($this->getContent()));
$excerpt = $this->noteUtil->stripMarkdown($this->getExcerptContent($maxlen));

Comment on lines +67 to +68

@enjeck enjeck Jun 22, 2026

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since this no longer goes through getContent(), it loses the non-UTF-8 handling done there. A UTF-16-encoded note that produced a readable excerpt before will now be read as raw bytes and decoded as UTF-8 below, yielding garbage?

$title = $this->getTitle();
if (!empty($title)) {
$length = mb_strlen($title, 'utf-8');
if (strncasecmp($excerpt, $title, $length) === 0) {
$excerpt = mb_substr($excerpt, $length, null, 'utf-8');
if ($title !== '') {
$titleLength = mb_strlen($title, 'utf-8');
if (strncasecmp($excerpt, $title, $titleLength) === 0) {
$excerpt = mb_substr($excerpt, $titleLength, null, 'utf-8');
}
}

$excerpt = trim($excerpt);

if (mb_strlen($excerpt, 'utf-8') > $maxlen) {
$excerpt = mb_substr($excerpt, 0, $maxlen, 'utf-8') . '…';
}
return str_replace("\n", "\u{2003}", $excerpt);
}

/**
* Lightweight best-effort content reader for excerpts only.
*/
private function getExcerptContent(int $maxlen) : string {
$handle = $this->file->fopen('r');
if (!is_resource($handle)) {
return '';
}

// Over-read bytes assuming worst-case UTF-8 size (up to 4 bytes per
// character). This is only a heuristic for preview generation; markdown
// stripping may reduce the visible character count further.
$bytesToRead = max(512, $maxlen * 4);

@enjeck enjeck Jun 22, 2026

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Maybe * 6 is better. With the default maxlen=100 this reads 512 bytes. After stripMarkdown() and the leading-title strip (lines 71–76), a long first line / URL / long title can push the visible excerpt below maxlen, where the old full-read produced a complete one


try {
$content = fread($handle, $bytesToRead);
if ($content === false) {
return '';
}
} finally {
fclose($handle);
}

// Remove any partial trailing multibyte character from the truncated read.
$content = mb_strcut($content, 0, strlen($content), 'UTF-8');
Comment on lines +108 to +109

@enjeck enjeck Jun 22, 2026

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I dont understand. The comment says this removes a partial trailing multibyte char, but passing strlen($content) (the full byte length) as the cut length makes it effectively a no-op for that purpos?


// Strip Byte Order Marks (BOM) for UTF-8, UTF-16 BE, and UTF-16 LE
$content = str_replace(["\xEF\xBB\xBF", "\xFE\xFF", "\xFF\xFE"], '', $content);
Comment on lines +111 to +112

@enjeck enjeck Jun 22, 2026

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The UTF-16 BOMs (\xFE\xFF, \xFF\xFE) are stripped here, but since the body isn't transcoded from UTF-16 (a i said at https://github.com/nextcloud/notes/pull/1886/changes#r3450190129) , the rest of a UTF-16 note is still mis-decoded?


return $content;
}

public function getModified() : int {
return $this->file->getMTime();
}
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