Performance optimizations: thread-safe date formatting, buffered I/O, efficient string operations

[Copilot]

Identified and fixed performance bottlenecks across Android and Web SDKs affecting multi-threaded logging, file I/O, and database operations.

Android SDK

Thread-safe SimpleDateFormat

• Replaced shared SimpleDateFormat instances with ThreadLocal to eliminate race conditions
• Affected: Util.java, LoganControlCenter.java

Buffered file I/O

• Wrapped file streams with BufferedInputStream/BufferedOutputStream in LoganThread.java
• Moved flush() outside write loop
• Expected: 2-5x faster file copy operations

Web SDK

Optimized UTF-8 byte size calculation

• utils.ts: Use native Blob API when available, fallback to manual calculation
• Expected: 10-100x speedup for large strings

Eliminated redundant encoding

• report-log.ts: Encode log items once, reuse result instead of double-encoding

// Before: encoded twice
const encoded = items.map(i => encodeURIComponent(i.logString));
// ... later
logArray: items.map(i => encodeURIComponent(i.logString)).toString()

// After: encode once, reuse
logArray: encoded.toString()

Batched database operations

• logan-db.ts: Use Set for O(1) lookups vs O(n) indexOf()
• Use map() instead of reduce() with concatenation
• Parallelize DB operations with Promise.all() instead of sequential await in loop

// Before: sequential DB operations
for (const pageIndex of reportedPageIndexes) {
    await this.DB.deleteItemsInRange([...]);
}

// After: parallel batch operation
await Promise.all([
    this.DB.addItems([updatedDayInfo]),
    this.DB.deleteItemsInRange(deleteOperations)
]);

Testing

• WebSDK: All 16 tests pass
• TypeScript compilation clean
• Java syntax validated

[!WARNING]

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• dl.google.com
  • Triggering command: /usr/lib/jvm/temurin-11-jdk-amd64/bin/java --add-opens java.base/java.util=ALL-UNNAMED --add-opens java.base/java.lang=ALL-UNNAMED --add-opens java.base/java.lang.invoke=ALL-UNNAMED --add-opens java.base/java.util=ALL-UNNAMED --add-opens java.prefs/java.util.prefs=ALL-UNNAMED --add-opens java.prefs/java.util.prefs=ALL-UNNAMED --add-opens java.base/java.nio.charset=ALL-UNNAMED --add-opens java.base/java.net=ALL-UNNAMED --add-opens java.base/java.util.concurrent.atomic=ALL-UNNAMED -Xmx1536m -Dfile.encoding=UTF-8 -Duser.country -Duser.language=en -Duser.variant -cp /home/REDACTED/.gradle/wrapper/dists/gradle-7.5-bin/f1w0cc9nuo0eivz97x2xlu9sv/gradle-7.5/lib/gradle-launcher-7.5.jar org.gradle.launcher.daemon.bootstrap.GradleDaemon 7.5 (dns block)
• mybatis.org
  • Triggering command: /opt/hostedtoolcache/CodeQL/2.23.1/x64/codeql/tools/linux64/java/bin/java -jar /opt/hostedtoolcache/CodeQL/2.23.1/x64/codeql/xml/tools/xml-extractor.jar --fileList=/home/REDACTED/work/Logan/.codeql-scratch/dbs/java/working/files-to-index8629952928232936764.list --sourceArchiveDir=/home/REDACTED/work/Logan/.codeql-scratch/dbs/java/src --outputDir=/home/REDACTED/work/Logan/.codeql-scratch/dbs/java/trap/java (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

Original prompt

Identify and suggest improvements to slow or inefficient code

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