More bugfixes to compress_filter.

Introduced grpc_metadata_batch_move and added grpc_compress_filter to grpc_server_create

src/core/channel/compress_filter.c

@@ -112,43 +112,51 @@ static int skip_compression(channel_data *channeld, call_data *calld) {
 
 static void finish_compressed_sopb(grpc_stream_op_buffer *send_ops,
                                    grpc_call_element *elem) {
-  size_t i, j;
+  size_t i;
+  grpc_stream_op_buffer new_send_ops;
   call_data *calld = elem->call_data;
   channel_data *channeld = elem->channel_data;
+  int new_slices_added = 0; /* GPR_FALSE */
+  grpc_metadata_batch metadata;
+
+  grpc_sopb_init(&new_send_ops);
 
   /* The following loop is akin to a selective reset + update */
-  for (i = 0, j = 0; i < send_ops->nops; ++i) {
+  for (i = 0; i < send_ops->nops; i++) {
     grpc_stream_op *sop = &send_ops->ops[i];
     switch (sop->type) {
       case GRPC_OP_BEGIN_MESSAGE:
-        sop->data.begin_message.length = calld->slices.length;
-        sop->data.begin_message.flags |= GRPC_WRITE_INTERNAL_COMPRESS;
+        grpc_sopb_add_begin_message(
+            &new_send_ops, calld->slices.length,
+            sop->data.begin_message.flags | GRPC_WRITE_INTERNAL_COMPRESS);
         break;
       case GRPC_OP_METADATA:
+        grpc_metadata_batch_move(&metadata, &sop->data.metadata);
         if (!calld->seen_initial_metadata) {
           grpc_metadata_batch_add_head(
-              &(sop->data.metadata), &calld->compression_algorithm_storage,
+              &metadata, &calld->compression_algorithm_storage,
               grpc_mdelem_ref(channeld->mdelem_compression_algorithms
                                   [calld->compression_algorithm]));
           calld->seen_initial_metadata = 1; /* GPR_TRUE */
         }
+        grpc_sopb_add_metadata(&new_send_ops, metadata);
         break;
       case GRPC_OP_SLICE:
-        gpr_slice_unref(sop->data.slice);
-        /* replace only up to the number of available compressed slices */
-        if (j < calld->slices.count) {
-          sop->data.slice = gpr_slice_ref(calld->slices.slices[j++]);
+        if (!new_slices_added) {
+          size_t j;
+          for (j = 0; j < calld->slices.count; ++j) {
+            grpc_sopb_add_slice(&new_send_ops,
+                                gpr_slice_ref(calld->slices.slices[j]));
+          }
+          new_slices_added = 1; /* GPR_TRUE */
         }
         break;
       case GRPC_NO_OP:
         break;
     }
   }
-
-  /* in case compressed slices remain to be added to the output */
-  while (j < calld->slices.count) {
-    grpc_sopb_add_slice(send_ops, gpr_slice_ref(calld->slices.slices[j++]));
-  }
+  grpc_sopb_swap(send_ops, &new_send_ops);
+  grpc_sopb_destroy(&new_send_ops);
 }
 
 /* even if the filter isn't producing compressed output, it may need to update

src/core/surface/server_create.c

@@ -34,7 +34,10 @@
 #include <grpc/grpc.h>
 #include "src/core/surface/completion_queue.h"
 #include "src/core/surface/server.h"
+#include "src/core/channel/compress_filter.h"
 
 grpc_server *grpc_server_create(const grpc_channel_args *args) {
-  return grpc_server_create_from_filters(NULL, 0, args);
+  const grpc_channel_filter *filters[] = {&grpc_compress_filter};
+  return grpc_server_create_from_filters(filters, GPR_ARRAY_SIZE(filters),
+                                         args);
 }

src/core/transport/stream_op.c

@@ -286,6 +286,12 @@ void grpc_metadata_batch_merge(grpc_metadata_batch *target,
   }
 }
 
+void grpc_metadata_batch_move(grpc_metadata_batch *dst,
+                               grpc_metadata_batch *src) {
+  *dst = *src;
+  memset(src, 0, sizeof(grpc_metadata_batch));
+}
+
 void grpc_metadata_batch_filter(grpc_metadata_batch *batch,
                                 grpc_mdelem *(*filter)(void *user_data,
                                                        grpc_mdelem *elem),

src/core/transport/stream_op.h

@@ -102,6 +102,11 @@ void grpc_metadata_batch_destroy(grpc_metadata_batch *batch);
 void grpc_metadata_batch_merge(grpc_metadata_batch *target,
                                grpc_metadata_batch *add);
 
+/** Moves the metadata information from \a src to \a dst. Upon return, \a src is
+ * zeroed. */
+void grpc_metadata_batch_move(grpc_metadata_batch *dst,
+                              grpc_metadata_batch *src);
+
 /** Add \a storage to the beginning of \a batch. storage->md is
     assumed to be valid. 
     \a storage is owned by the caller and must survive for the