fix the batch size not respected issue

libraries/apollo-runtime/src/commonMain/kotlin/com/apollographql/apollo/network/http/BatchingHttpInterceptor.kt

@@ -103,22 +103,31 @@ class BatchingHttpInterceptor @JvmOverloads constructor(
     val sendNow = mutex.withLock {
       // if there was an error, the previous job was already canceled, ignore that error
       pendingRequests.add(pendingRequest)
-      pendingRequests.size >= maxBatchSize
+      val batchFull = pendingRequests.size >= maxBatchSize
+      if (batchFull) {
+        executePendingRequests(needLock = false)
+      }
+      batchFull
     }
-    if (sendNow) {
-      executePendingRequests()
-    } else {
+
+    if (!sendNow) {
       scope.launch {
         delay(batchIntervalMillis - (startMark.elapsedNow().inWholeMilliseconds % batchIntervalMillis) - 1)
-        executePendingRequests()
+        executePendingRequests(needLock = true)
       }
     }
 
     return pendingRequest.deferred.await()
   }
 
-  private suspend fun executePendingRequests() {
-    val pending = mutex.withLock {
+  private suspend fun executePendingRequests(needLock: Boolean) {
+    val pending = if (needLock) {
+      mutex.withLock {
+        val copy = pendingRequests.toList()
+        pendingRequests.clear()
+        copy
+      }
+    } else {
       val copy = pendingRequests.toList()
       pendingRequests.clear()
       copy

tests/integration-tests/src/commonTest/kotlin/test/batching/QueryBatchingTest.kt

@@ -4,15 +4,22 @@ import batching.GetLaunch2Query
 import batching.GetLaunchQuery
 import com.apollographql.apollo.ApolloClient
 import com.apollographql.apollo.api.AnyAdapter
+import com.apollographql.apollo.api.ApolloResponse
 import com.apollographql.apollo.api.CustomScalarAdapters
 import com.apollographql.apollo.api.ExecutionOptions.Companion.CAN_BE_BATCHED
 import com.apollographql.apollo.api.http.HttpHeader
 import com.apollographql.apollo.api.json.jsonReader
+import com.apollographql.apollo.testing.internal.runTest
+import com.apollographql.mockserver.MockRequest
+import com.apollographql.mockserver.MockRequestBase
+import com.apollographql.mockserver.MockResponse
 import com.apollographql.mockserver.MockServer
+import com.apollographql.mockserver.MockServerHandler
 import com.apollographql.mockserver.awaitRequest
 import com.apollographql.mockserver.enqueueString
-import com.apollographql.apollo.testing.internal.runTest
+import kotlinx.coroutines.Deferred
 import kotlinx.coroutines.async
+import kotlinx.coroutines.awaitAll
 import kotlinx.coroutines.delay
 import okio.Buffer
 import kotlin.test.Ignore
@@ -21,7 +28,9 @@ import kotlin.test.assertEquals
 import kotlin.test.assertFails
 import kotlin.test.assertFalse
 import kotlin.test.assertIs
+import kotlin.test.assertNotNull
 import kotlin.test.assertTrue
+import kotlin.time.Duration.Companion.seconds
 
 class QueryBatchingTest {
   private lateinit var mockServer: MockServer
@@ -90,7 +99,7 @@ class QueryBatchingTest {
 
     // Only one request must have been sent
     assertFails {
-      mockServer.awaitRequest()
+      mockServer.awaitRequest(3.seconds)
     }
   }
 
@@ -217,7 +226,7 @@ class QueryBatchingTest {
 
     // Only one request must have been sent
     assertFails {
-      mockServer.awaitRequest()
+      mockServer.awaitRequest(3.seconds)
     }
   }
 
@@ -251,7 +260,7 @@ class QueryBatchingTest {
     val request = mockServer.awaitRequest()
     // Only one request must have been sent
     assertFails {
-      mockServer.awaitRequest()
+      mockServer.awaitRequest(3.seconds)
     }
     assertTrue(request.headers["client0"] == "0")
     assertTrue(request.headers["client1"] == "1")
@@ -296,4 +305,45 @@ class QueryBatchingTest {
     assertFalse(request.headers.keys.contains("query1+query2-different-value"))
     assertFalse(request.headers.keys.contains(CAN_BE_BATCHED))
   }
+
+  @Test
+  fun batchSizeIsHonoredWithConcurrency() = runTest(before = { setUp() }, after = { tearDown() }) {
+    mockServer.close()
+    mockServer = MockServer.Builder().handler(object : MockServerHandler {
+      override fun handle(request: MockRequestBase): MockResponse {
+        val jsonReader = Buffer().write((request as MockRequest).body).jsonReader()
+        jsonReader.beginArray()
+        var arrayLength = 0
+        while (jsonReader.hasNext()) {
+          jsonReader.skipValue()
+          arrayLength++
+        }
+
+        // Check we never receive more than maxBatchSize queries
+        assertTrue(arrayLength <= 10)
+
+        return MockResponse.Builder()
+            .body("[" + List(arrayLength) { """{"data":{"launch":{"id":"83"}}}""" }.joinToString() + "]")
+            .build()
+      }
+    }).build()
+
+    apolloClient = ApolloClient.Builder()
+        .serverUrl(mockServer.url())
+        .httpBatching(maxBatchSize = 10, batchIntervalMillis = 10)
+        .build()
+
+    val deferredResults = mutableListOf<Deferred<ApolloResponse<GetLaunchQuery.Data>>>()
+    repeat(100) {
+      deferredResults += async {
+        delay(1)
+        apolloClient.query(GetLaunchQuery())
+            .canBeBatched(true)
+            .execute()
+      }
+    }
+    for (apolloResponse in deferredResults.awaitAll()) {
+      assertNotNull(apolloResponse.data)
+    }
+  }
 }