Improved git diff performance by using coroutines

src/main/kotlin/Diff.kt

@@ -5,9 +5,13 @@ import androidx.compose.foundation.layout.fillMaxWidth
 import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.lazy.LazyColumn
 import androidx.compose.foundation.lazy.items
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.setValue
 import androidx.compose.foundation.text.selection.SelectionContainer
 import androidx.compose.material.*
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.LaunchedEffect
+import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
@@ -19,10 +23,13 @@ import theme.primaryTextColor
 
 @Composable
 fun Diff(gitManager: GitManager, diffEntryType: DiffEntryType, onCloseDiffView: () -> Unit) {
-    val text = remember(diffEntryType.diffEntry) {
+    var text by remember { mutableStateOf(listOf<String>()) }
-        gitManager.diffFormat(diffEntryType)
+
+    LaunchedEffect(diffEntryType.diffEntry) {
+        text = gitManager.diffFormat(diffEntryType)
     }
 
+
     Card(
         modifier = Modifier
             .padding(8.dp)

src/main/kotlin/GitManager.kt

@@ -1,10 +1,7 @@
 import git.*
-import kotlinx.coroutines.CancellationException
+import kotlinx.coroutines.*
-import kotlinx.coroutines.CoroutineScope
-import kotlinx.coroutines.SupervisorJob
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.StateFlow
-import kotlinx.coroutines.launch
 import org.eclipse.jgit.api.Git
 import org.eclipse.jgit.diff.DiffEntry
 import org.eclipse.jgit.diff.DiffFormatter
@@ -24,6 +21,7 @@ class GitManager {
     private val remoteOperationsManager = RemoteOperationsManager()
     private val branchesManager = BranchesManager()
     private val stashManager = StashManager()
+    private val diffManager = DiffManager()
 
     private val managerScope = CoroutineScope(SupervisorJob())
 
@@ -126,31 +124,8 @@ class GitManager {
     val hasUncommitedChanges: StateFlow<Boolean>
         get() = statusManager.hasUncommitedChanges
 
-    fun diffFormat(diffEntryType: DiffEntryType): List<String> {
+    suspend fun diffFormat(diffEntryType: DiffEntryType): List<String> {
-        val diffEntry = diffEntryType.diffEntry
+        return diffManager.diffFormat(safeGit, diffEntryType)
-        val byteArrayOutputStream = ByteArrayOutputStream()
-
-        DiffFormatter(byteArrayOutputStream).use { formatter ->
-            val repo = safeGit.repository
-            formatter.setRepository(repo)
-
-            val oldTree = DirCacheIterator(repo.readDirCache())
-            val newTree = FileTreeIterator(repo)
-
-            if (diffEntryType is DiffEntryType.UnstagedDiff)
-                formatter.scan(oldTree, newTree)
-
-            formatter.format(diffEntry)
-            formatter.flush()
-        }
-
-        val diff = byteArrayOutputStream.toString(Charsets.UTF_8)
-
-        // TODO This is just a workaround, try to find properly which lines have to be displayed by using a custom diff
-
-        return diff.split("\n", "\r\n").filterNot {
-            it.startsWith("diff --git")
-        }
     }
 
     fun pull() = managerScope.launch {

src/main/kotlin/git/DiffManager.kt

@@ -0,0 +1,40 @@
+package git
+
+import DiffEntryType
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.withContext
+import org.eclipse.jgit.api.Git
+import org.eclipse.jgit.diff.DiffFormatter
+import org.eclipse.jgit.dircache.DirCacheIterator
+import org.eclipse.jgit.treewalk.FileTreeIterator
+import java.io.ByteArrayOutputStream
+
+class DiffManager {
+    suspend fun diffFormat(git: Git, diffEntryType: DiffEntryType): List<String> = withContext(Dispatchers.IO) {
+        val diffEntry = diffEntryType.diffEntry
+        val byteArrayOutputStream = ByteArrayOutputStream()
+
+        DiffFormatter(byteArrayOutputStream).use { formatter ->
+            val repo = git.repository
+            formatter.setRepository(repo)
+
+            val oldTree = DirCacheIterator(repo.readDirCache())
+            val newTree = FileTreeIterator(repo)
+
+            if (diffEntryType is DiffEntryType.UnstagedDiff)
+                formatter.scan(oldTree, newTree)
+
+            formatter.format(diffEntry)
+            formatter.flush()
+        }
+
+        val diff = byteArrayOutputStream.toString(Charsets.UTF_8)
+
+        // TODO This is just a workaround, try to find properly which lines have to be displayed by using a custom diff
+
+        return@withContext diff.split("\n", "\r\n").filterNot {
+            it.startsWith("diff --git")
+        }
+
+    }
+}