perf: Replace java.net.URI with custom string parsing in Dsn

[runningcode]

Summary

• Replace new URI(dsnString).normalize() in the Dsn constructor with manual indexOf/substring parsing to avoid the slow java.net.URI parser on Android
• retrieveParsedDsn() is called on the main thread during Sentry.init() → preInitConfigurations(), so this directly impacts app startup time
• The only remaining URI construction is from pre-parsed components (new URI(scheme, null, host, port, path, null, null)), which is much cheaper since it doesn't re-parse a string

Relates to: https://linear.app/getsentry/issue/JAVA-516/move-dsn-parsing-off-the-main-thread-during-init

🤖 Generated with Claude Code

[linear-code]

JAVA-516

[sentry]

📲 Install Builds

Android

🔗 App Name	App ID	Version	Configuration
SDK Size	io.sentry.tests.size	8.41.0 (1)	release

⚙️ sentry-android Build Distribution Settings

[github-actions]

Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	354.34 ms	443.40 ms	89.06 ms
Size	0 B	0 B	0 B

Baseline results on branch: main

Startup times

Revision	Plain	With Sentry	Diff
27d7cf8	309.43 ms	364.27 ms	54.85 ms
ee35ac3	346.83 ms	435.48 ms	88.65 ms
2124a46	319.19 ms	415.04 ms	95.85 ms
f6cdbf0	314.19 ms	357.59 ms	43.40 ms
22f4345	325.23 ms	454.66 ms	129.43 ms
fcec2f2	357.47 ms	447.32 ms	89.85 ms
f064536	329.00 ms	395.62 ms	66.62 ms
bb0ff41	344.70 ms	413.82 ms	69.12 ms
d15471f	361.89 ms	378.07 ms	16.18 ms
e59e22a	368.02 ms	432.00 ms	63.98 ms

App size

Revision	Plain	With Sentry	Diff
27d7cf8	1.58 MiB	2.12 MiB	549.42 KiB
ee35ac3	1.58 MiB	2.13 MiB	558.77 KiB
2124a46	1.58 MiB	2.12 MiB	551.51 KiB
f6cdbf0	0 B	0 B	0 B
22f4345	1.58 MiB	2.29 MiB	719.83 KiB
fcec2f2	1.58 MiB	2.12 MiB	551.50 KiB
f064536	1.58 MiB	2.20 MiB	633.90 KiB
bb0ff41	0 B	0 B	0 B
d15471f	1.58 MiB	2.13 MiB	559.54 KiB
e59e22a	1.58 MiB	2.20 MiB	635.34 KiB

[cursor]

Cursor Bugbot has reviewed your changes and found 2 potential issues.

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[cursor]

URI fragment not stripped, corrupts projectId silently

Low Severity

The new parser strips query strings (?...) but never strips URI fragments (#...). The old java.net.URI.getPath() automatically excluded fragments. If a DSN contains a # (e.g. https://key@host/123#frag), the fragment leaks into projectId (becoming 123#frag), and the multi-arg URI constructor percent-encodes # as %23, producing an incorrect sentryUri path. The queryIndex stripping logic at line 100 needs a similar check for #.

Additional Locations (1)

• sentry/src/main/java/io/sentry/Dsn.java#L137-L138

 

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[cursor]

IPv6 host parsing broken by first-colon port detection

Low Severity

hostPort.indexOf(':') finds the first colon, which for IPv6 literals like [::1] or [::1]:9000 matches a colon inside the brackets rather than the port separator. This causes host to be [ and Integer.parseInt to throw on the remaining garbage. The old java.net.URI parser handled IPv6 bracket syntax correctly. Self-hosted Sentry users with IPv6 addresses would be unable to initialize the SDK.

 

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[0xadam-brown]

A few optionals; otherwise lgtm

[0xadam-brown]

l: Thoughts about extracting logic into static methods for legibility? Something like:

        try {
          final String s  = requireValid(dsn);
          final String scheme  = extractScheme(s);

          final String userInfo  = extractUserInfo(s);
          final int keyColon  = userInfo.indexOf(':');
          this.publicKey = keyColon < 0 ? userInfo : userInfo.substring(0, keyColon);
          this.secretKey = keyColon < 0 ? null : userInfo.substring(keyColon + 1);
          if (this.publicKey.isEmpty()) {
              throw new IllegalArgumentException("Invalid DSN: No public key provided.");
          }
  
          final String hostPort = extractHostPort(s);
          final int portColon = hostPort.indexOf(':');
          final String host = portColon < 0 ? hostPort : hostPort.substring(0, portColon);
          final int port = portColon < 0 ? -1 : Integer.parseInt(hostPort.substring(portColon + 1));
  
          final String rawPath = extractNormalizedPath(s);
          this.path = extractPathSegment(rawPath);
          final String projectId = extractProjectId(rawPath);
          this.projectId = projectId;

          this.sentryUri = buildSentryUri(scheme, host, port, this.path, projectId);
          this.orgId = extractOrgId(host);
      } catch (Throwable e) {
          throw new IllegalArgumentException(e);
      }

Claude thinks HotSpot, dex2oat, etc. would inline the invocations, meaning no practical overhead.

Up to you, of course.

[0xadam-brown]

Strip any fragment too?

 final int fragmentIndex = dsnString.indexOf('#', hostStart);

URI would've done it. Not sure how much we care about saving folks from obvious errors they're unlikely to make, but including it will keep parity.

[0xadam-brown]

...ah, cursorbot beat me to it.

[0xadam-brown]

l: We could give a more informative error message if the port is malformed / not an int:

final String portStr = hostPort.substring(portColon + 1);
  try {
      port = Integer.parseInt(portStr);
  } catch (NumberFormatException e) {
      throw new IllegalArgumentException("Invalid DSN: invalid port: " + portStr);
  }

(Presumably rare in practice, and cleaner to do if we extract logic into static methods. Also up to you.)

[0xadam-brown]

l: My vote would be for asserting particular error messages in these tests, as they're part of our implicit API. (Looks like we sometimes do it above.)