Optimize nested loops, string concatenation, and repeated sorting

[Copilot]

Identified and fixed several algorithmic and memory allocation bottlenecks causing poor performance in list operations, database queries, and UI rendering.

Changes

Nested loop elimination (O(n²) → O(n))

• AdapterRule: Use HashMap for related package lookups instead of nested iteration
• BlocklistManager: Use HashSet for orphaned file detection instead of nested loops

String concatenation in hot paths

• DatabaseHelper: Replace += with StringBuilder in 11 SQL query building methods
• Eliminates intermediate String object creation on every append

Repeated sorting in UI rendering

• Tracker: Add lazy-initialized sorted hosts cache
• TrackersListAdapter: Use cached sort instead of allocating + sorting ArrayList on every bind

Example

Before (line 1043-1056 in AdapterRule):

for (String pkg : rule.related) {
    for (Rule related : listAll)
        if (related.packageName.equals(pkg)) {
            // update related rule
        }
}

After:

HashMap<String, Rule> packageMap = new HashMap<>();
for (Rule r : listAll) packageMap.put(r.packageName, r);
for (String pkg : rule.related) {
    Rule related = packageMap.get(pkg);
    if (related != null) { /* update */ }
}

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-17-jdk-amd64/bin/java /usr/lib/jvm/temurin-17-jdk-amd64/bin/java --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-exports=jdk.compiler/com.sun.tools.javac.api=ALL-UNNAMED --add-exports=jdk.compiler/com.sun.tools.javac.util=ALL-UNNAMED --add-opens=java.base/java.util=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 --add-opens=java.xml/javax.xml.namespace=ALL-UNNAMED -Xmx4608m -Dfile.encoding=UTF-8 -Duser.country -Duser.language=en -Duser.variant -cp /home/REDACTED/.gradle/wrapper/dists/gradle-8.13-bin/5xuhj0ry160q40clulazy9h7d/gradle-8.13/lib/gradle-daemon-main-8.13.jar (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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[kasnder]

What's the expected speed up of this? Appears rather minimal?