A few improvements to logging when lldb-dap is started in Server Mode AND when the lldb-dap.logFolder setting is used (not lldb-dap.log-path).

Improvement #1

Avoid the prompt of restarting the server at the start of each debug session.

That prompt is caused by the combination of the following facts:

1. The log filename changes every time a new debug session is starting (see here)
2. The log filename is passed to the server via an environment variable called "LLDBDAP_LOG" (see here)
3. All environment variables are put into the "spawn info" variable (see here).
4. The old and new "spawn info" are compared to decide if a prompt should show (see here).

The fix is to remove the "LLDBDAP_LOG" from the "spawn info" variable, so that the same server can be reused if the log path is the only thing that has changed.

Improvement #2

Avoid log file conflict when multiple users share a machine and start server in the same second.

The problem: If two users start lldb-dap server in the same second, they will share the same log path. The first user will create the log file, and the second the user will find that they cannot access the same file, so their server will fail to start.

The fix is to add username to the log path.

Limitation: In theory, one user can start two server in the same second to have the same access violation. However, to hit this issue, they will have to start the debug sessions in two separate VS Code instances (and thus two lldb-dap extensions). I'm not sure how common that is. A more correct fix would be to use some kind of session UUID. It seems we don't have that concept at least yet.

Improvement #3

Avoid restarting the server when the order of environment variables changed.

This is done by sorting the environment variables before putting them into the "spawn info".

Full diff: https://github.com/llvm/llvm-project/pull/159672.diff

2 Files Affected:

• (modified) lldb/tools/lldb-dap/src-ts/lldb-dap-server.ts (+6-3)
• (modified) lldb/tools/lldb-dap/src-ts/logging.ts (+2-1)

diff --git a/lldb/tools/lldb-dap/src-ts/lldb-dap-server.ts b/lldb/tools/lldb-dap/src-ts/lldb-dap-server.ts
index 774be50053a17..280a11d807f6a 100644
--- a/lldb/tools/lldb-dap/src-ts/lldb-dap-server.ts
+++ b/lldb/tools/lldb-dap/src-ts/lldb-dap-server.ts
@@ -167,9 +167,12 @@ Restarting the server will interrupt any existing debug sessions and start a new
     return [
       path,
       ...args,
-      ...Object.entries(env ?? {}).map(
-        (entry) => String(entry[0]) + "=" + String(entry[1]),
-      ),
+      ...Object.entries(env ?? {})
+        // Filter and sort to avoid restarting the server just because the
+        // order of env changed or the log path changed.
+        .filter((entry) => String(entry[0]) !== "LLDBDAP_LOG")
+        .sort()
+        .map((entry) => String(entry[0]) + "=" + String(entry[1])),
     ];
   }
 }
diff --git a/lldb/tools/lldb-dap/src-ts/logging.ts b/lldb/tools/lldb-dap/src-ts/logging.ts
index 3b1c3c37ce1ce..e3b6c56291cec 100644
--- a/lldb/tools/lldb-dap/src-ts/logging.ts
+++ b/lldb/tools/lldb-dap/src-ts/logging.ts
@@ -1,3 +1,4 @@
+import * as os from 'os';
 import * as path from "path";
 import * as vscode from "vscode";
 
@@ -44,7 +45,7 @@ export class LogFilePathProvider {
     const logFolder = this.logFolder || this.context.logUri.fsPath;
     switch(type) {
     case LogType.DEBUG_SESSION:
-        return path.join(logFolder, `lldb-dap-session-${formatDate(new Date())}.log`);
+        return path.join(logFolder, `lldb-dap-session-${os.userInfo().username}-${formatDate(new Date())}.log`);
         break;
     }
   }