Remove metadata context from the channel stack

4 files changed, 278 insertions, 138 deletions

diff --git a/src/core/transport/metadata.c b/src/core/transport/metadata.c
index fa941a73c6..cbec63c868 100644
--- a/src/core/transport/metadata.c
+++ b/src/core/transport/metadata.c
@@ -37,12 +37,15 @@
 #include <stddef.h>
 #include <string.h>
 
+#include <grpc/compression.h>
 #include <grpc/support/alloc.h>
 #include <grpc/support/atm.h>
 #include <grpc/support/log.h>
+#include <grpc/support/string_util.h>
 #include <grpc/support/time.h>
 #include "src/core/profiling/timers.h"
 #include "src/core/support/murmur_hash.h"
+#include "src/core/support/string.h"
 #include "src/core/transport/chttp2/bin_encoder.h"
 #include "src/core/transport/static_metadata.h"
 
@@ -157,6 +160,11 @@ struct grpc_mdctx {
   size_t mdtab_count;
   size_t mdtab_free;
   size_t mdtab_capacity;
+
+  /* cache slots */
+  gpr_atm cache_slots[GRPC_MDELEM_CACHE_SLOT_COUNT];
+  /* compression algorithm mdelems: one per algorithm bitmask */
+  gpr_atm compression_algorithm_mdelem[1 << GRPC_COMPRESS_ALGORITHMS_COUNT];
 };
 
 static void internal_string_ref(internal_string *s DEBUG_ARGS);
@@ -175,8 +183,10 @@ void grpc_mdctx_global_init(void) {
   }
   for (i = 0; i < GRPC_STATIC_MDELEM_COUNT; i++) {
     grpc_mdelem *elem = &grpc_static_mdelem_table[i];
-    grpc_mdstr *key = &grpc_static_mdstr_table[2 * i + 0];
-    grpc_mdstr *value = &grpc_static_mdstr_table[2 * i + 1];
+    grpc_mdstr *key =
+        &grpc_static_mdstr_table[grpc_static_metadata_elem_indices[2 * i + 0]];
+    grpc_mdstr *value =
+        &grpc_static_mdstr_table[grpc_static_metadata_elem_indices[2 * i + 1]];
     *(grpc_mdstr **)&elem->key = key;
     *(grpc_mdstr **)&elem->value = value;
   }
@@ -304,6 +314,42 @@ grpc_mdctx *grpc_mdctx_create(void) {
       (gpr_uint32)gpr_now(GPR_CLOCK_REALTIME).tv_nsec);
 }
 
+static void drop_cached_elem(gpr_atm *slot) {
+  gpr_atm value = gpr_atm_no_barrier_load(slot);
+  gpr_atm_rel_store(slot, 0);
+  GRPC_MDELEM_UNREF((grpc_mdelem *)value);
+}
+
+void grpc_mdctx_drop_caches(grpc_mdctx *ctx) {
+  size_t i;
+  for (i = 0; i < GRPC_MDELEM_CACHE_SLOT_COUNT; i++) {
+    drop_cached_elem(&ctx->cache_slots[i]);
+  }
+  for (i = 0; i < GPR_ARRAY_SIZE(ctx->compression_algorithm_mdelem); i++) {
+    drop_cached_elem(&ctx->compression_algorithm_mdelem[i]);
+  }
+}
+
+static void set_cache(gpr_atm *slot, grpc_mdelem *elem) {
+  if (!gpr_atm_rel_cas(slot, 0, (gpr_atm)elem)) {
+    GRPC_MDELEM_UNREF(elem);
+  }
+}
+
+void grpc_mdctx_set_mdelem_cache(grpc_mdctx *ctx, grpc_mdelem_cache_slot slot,
+                                 grpc_mdelem *elem) {
+  set_cache(&ctx->cache_slots[slot], elem);
+}
+
+static grpc_mdelem *get_cache(gpr_atm *slot) {
+  return (grpc_mdelem *)gpr_atm_acq_load(slot);
+}
+
+grpc_mdelem *grpc_mdelem_from_cache(grpc_mdctx *ctx,
+                                    grpc_mdelem_cache_slot slot) {
+  return get_cache(&ctx->cache_slots[slot]);
+}
+
 static void discard_metadata(grpc_mdctx *ctx) {
   size_t i;
   internal_metadata *next, *cur;
@@ -780,6 +826,7 @@ void *grpc_mdelem_get_user_data(grpc_mdelem *md, void (*destroy_func)(void *)) {
 void grpc_mdelem_set_user_data(grpc_mdelem *md, void (*destroy_func)(void *),
                                void *user_data) {
   internal_metadata *im = (internal_metadata *)md;
+  GPR_ASSERT(!is_mdelem_static(md));
   GPR_ASSERT((user_data == NULL) == (destroy_func == NULL));
   gpr_mu_lock(&im->mu_user_data);
   if (gpr_atm_no_barrier_load(&im->destroy_user_data)) {
@@ -838,6 +885,52 @@ int grpc_mdstr_is_legal_nonbin_header(grpc_mdstr *s) {
   return conforms_to(s, legal_header_bits);
 }
 
+static grpc_mdelem *make_accept_encoding_mdelem_for_compression_algorithms(
+    grpc_mdctx *mdctx, gpr_uint32 algorithms) {
+  gpr_strvec sv;
+  int i;
+  char *str;
+  grpc_mdelem *out;
+
+  gpr_strvec_init(&sv);
+  for (i = 0; algorithms != 0; i++, algorithms >>= 1) {
+    if (algorithms & 1) {
+      char *name;
+      GPR_ASSERT(grpc_compression_algorithm_name((grpc_compression_algorithm)i,
+                                                 &name));
+      if (sv.count) {
+        gpr_strvec_add(&sv, gpr_strdup(","));
+      }
+      gpr_strvec_add(&sv, gpr_strdup(name));
+    }
+  }
+  str = gpr_strvec_flatten(&sv, NULL);
+  out =
+      grpc_mdelem_from_metadata_strings(mdctx, GRPC_MDSTR_GRPC_ACCEPT_ENCODING,
+                                        grpc_mdstr_from_string(mdctx, str));
+  gpr_strvec_destroy(&sv);
+  gpr_free(str);
+  return out;
+}
+
+grpc_mdelem *grpc_accept_encoding_mdelem_from_compression_algorithms(
+    grpc_mdctx *ctx, gpr_uint32 algorithms) {
+  grpc_mdelem *ret;
+  gpr_atm *slot;
+  GPR_ASSERT(algorithms < GPR_ARRAY_SIZE(ctx->compression_algorithm_mdelem));
+
+  slot = &ctx->compression_algorithm_mdelem[algorithms];
+  ret = get_cache(slot);
+  if (ret == NULL) {
+    set_cache(slot, make_accept_encoding_mdelem_for_compression_algorithms(
+                        ctx, algorithms));
+    ret = get_cache(slot);
+    GPR_ASSERT(ret != NULL);
+  }
+
+  return ret;
+}
+
 int grpc_mdstr_is_bin_suffixed(grpc_mdstr *s) {
   /* TODO(ctiller): consider caching this */
   return grpc_is_binary_header((const char *)GPR_SLICE_START_PTR(s->slice),
diff --git a/src/core/transport/metadata.h b/src/core/transport/metadata.h
index 7d70883fa4..0f12a7392c 100644
--- a/src/core/transport/metadata.h
+++ b/src/core/transport/metadata.h
@@ -93,6 +93,8 @@ grpc_mdctx *grpc_mdctx_create_with_seed(gpr_uint32 seed);
 void grpc_mdctx_ref(grpc_mdctx *mdctx);
 void grpc_mdctx_unref(grpc_mdctx *mdctx);
 
+void grpc_mdctx_drop_caches(grpc_mdctx *mdctx);
+
 /* Test only accessors to internal state - only for testing this code - do not
    rely on it outside of metadata_test.c */
 size_t grpc_mdctx_get_mdtab_capacity_test_only(grpc_mdctx *mdctx);
@@ -161,6 +163,25 @@ int grpc_mdstr_is_legal_header(grpc_mdstr *s);
 int grpc_mdstr_is_legal_nonbin_header(grpc_mdstr *s);
 int grpc_mdstr_is_bin_suffixed(grpc_mdstr *s);
 
+/* Gross layering hack (that we seem to need):
+ * metadata context keeps a cache of algorithm bitset to
+ * 'accept-encoding: algorithm1,algorithm2' in order to accelerate sending
+ * compression metadata */
+grpc_mdelem *grpc_accept_encoding_mdelem_from_compression_algorithms(
+    grpc_mdctx *ctx, gpr_uint32 algorithm_mask);
+
+/* Cache-slots
+ * A metadata context can cache (on behalf of its owner) some small set of
+ * metadata elements. */
+typedef enum {
+  GRPC_MDELEM_CACHED_USER_AGENT = 0,
+  GRPC_MDELEM_CACHE_SLOT_COUNT
+} grpc_mdelem_cache_slot;
+void grpc_mdctx_set_mdelem_cache(grpc_mdctx *ctx, grpc_mdelem_cache_slot slot,
+                                 grpc_mdelem *elem);
+grpc_mdelem *grpc_mdelem_from_cache(grpc_mdctx *ctx,
+                                    grpc_mdelem_cache_slot slot);
+
 #define GRPC_MDSTR_KV_HASH(k_hash, v_hash) (GPR_ROTL((k_hash), 2) ^ (v_hash))
 
 void grpc_mdctx_global_init(void);
diff --git a/src/core/transport/static_metadata.c b/src/core/transport/static_metadata.c
index f359ce5c20..fb7c5006e1 100644
--- a/src/core/transport/static_metadata.c
+++ b/src/core/transport/static_metadata.c
@@ -47,18 +47,21 @@ grpc_mdstr grpc_static_mdstr_table[GRPC_STATIC_MDSTR_COUNT];
 
 grpc_mdelem grpc_static_mdelem_table[GRPC_STATIC_MDELEM_COUNT];
 
-const gpr_uint8 grpc_static_metadata_elem_indices[GRPC_STATIC_MDELEM_COUNT *
-                                                  2] = {
-    9,  29, 8,  29, 10, 29, 10, 42, 11, 29, 12, 29, 13, 29, 14, 29, 15, 29, 16,
-    29, 17, 29, 18, 29, 19, 29, 20, 29, 21, 29, 22, 29, 23, 29, 24, 29, 25, 29,
-    26, 29, 27, 29, 30, 29, 31, 29, 32, 29, 33, 29, 39, 0,  43, 29, 47, 29, 48,
-    29, 49, 29, 50, 29, 51, 29, 52, 29, 53, 29, 54, 29, 55, 29, 56, 34, 56, 58,
-    57, 68, 57, 69, 59, 29, 60, 29, 61, 29, 62, 29, 63, 29, 64, 29, 65, 35, 65,
-    44, 65, 45, 66, 29, 67, 29, 70, 1,  70, 2,  70, 3,  70, 4,  70, 5,  70, 6,
-    70, 7,  71, 29, 72, 73, 74, 29, 75, 29, 76, 29, 77, 29, 78, 29};
+const gpr_uint8
+    grpc_static_metadata_elem_indices[GRPC_STATIC_MDELEM_COUNT * 2] = {
+        11, 32, 10, 32, 12, 32, 12, 46, 13, 32, 14, 32, 15, 32, 16, 32, 17, 32,
+        19, 32, 20, 32, 21, 32, 22, 32, 23, 32, 24, 32, 25, 32, 26, 32, 27, 32,
+        28, 18, 28, 32, 29, 32, 30, 32, 33, 32, 34, 32, 35, 32, 36, 32, 40, 31,
+        40, 45, 40, 50, 43, 0,  43, 1,  43, 2,  47, 32, 51, 32, 52, 32, 53, 32,
+        54, 32, 55, 32, 56, 32, 57, 32, 58, 32, 59, 32, 60, 37, 60, 62, 61, 72,
+        61, 73, 63, 32, 64, 32, 65, 32, 66, 32, 67, 32, 68, 32, 69, 38, 69, 48,
+        69, 49, 70, 32, 71, 32, 74, 3,  74, 4,  74, 5,  74, 6,  74, 7,  74, 8,
+        74, 9,  75, 32, 76, 77, 78, 32, 79, 32, 80, 32, 81, 32, 82, 32};
 
 const char *const grpc_static_metadata_strings[GRPC_STATIC_MDSTR_COUNT] = {
     "0",
+    "1",
+    "2",
     "200",
     "204",
     "206",
@@ -74,6 +77,7 @@ const char *const grpc_static_metadata_strings[GRPC_STATIC_MDSTR_COUNT] = {
     "access-control-allow-origin",
     "age",
     "allow",
+    "application/grpc",
     ":authority",
     "authorization",
     "cache-control",
@@ -96,6 +100,7 @@ const char *const grpc_static_metadata_strings[GRPC_STATIC_MDSTR_COUNT] = {
     "grpc",
     "grpc-accept-encoding",
     "grpc-encoding",
+    "grpc-internal-encoding-request",
     "grpc-message",
     "grpc-status",
     "grpc-timeout",
diff --git a/src/core/transport/static_metadata.h b/src/core/transport/static_metadata.h
index 4a7bee1da8..671801636b 100644
--- a/src/core/transport/static_metadata.h
+++ b/src/core/transport/static_metadata.h
@@ -46,168 +46,176 @@
 
 #include "src/core/transport/metadata.h"
 
-#define GRPC_STATIC_MDSTR_COUNT 79
+#define GRPC_STATIC_MDSTR_COUNT 83
 extern grpc_mdstr grpc_static_mdstr_table[GRPC_STATIC_MDSTR_COUNT];
 /* "0" */
 #define GRPC_MDSTR_0 (&grpc_static_mdstr_table[0])
+/* "1" */
+#define GRPC_MDSTR_1 (&grpc_static_mdstr_table[1])
+/* "2" */
+#define GRPC_MDSTR_2 (&grpc_static_mdstr_table[2])
 /* "200" */
-#define GRPC_MDSTR_200 (&grpc_static_mdstr_table[1])
+#define GRPC_MDSTR_200 (&grpc_static_mdstr_table[3])
 /* "204" */
-#define GRPC_MDSTR_204 (&grpc_static_mdstr_table[2])
+#define GRPC_MDSTR_204 (&grpc_static_mdstr_table[4])
 /* "206" */
-#define GRPC_MDSTR_206 (&grpc_static_mdstr_table[3])
+#define GRPC_MDSTR_206 (&grpc_static_mdstr_table[5])
 /* "304" */
-#define GRPC_MDSTR_304 (&grpc_static_mdstr_table[4])
+#define GRPC_MDSTR_304 (&grpc_static_mdstr_table[6])
 /* "400" */
-#define GRPC_MDSTR_400 (&grpc_static_mdstr_table[5])
+#define GRPC_MDSTR_400 (&grpc_static_mdstr_table[7])
 /* "404" */
-#define GRPC_MDSTR_404 (&grpc_static_mdstr_table[6])
+#define GRPC_MDSTR_404 (&grpc_static_mdstr_table[8])
 /* "500" */
-#define GRPC_MDSTR_500 (&grpc_static_mdstr_table[7])
+#define GRPC_MDSTR_500 (&grpc_static_mdstr_table[9])
 /* "accept" */
-#define GRPC_MDSTR_ACCEPT (&grpc_static_mdstr_table[8])
+#define GRPC_MDSTR_ACCEPT (&grpc_static_mdstr_table[10])
 /* "accept-charset" */
-#define GRPC_MDSTR_ACCEPT_CHARSET (&grpc_static_mdstr_table[9])
+#define GRPC_MDSTR_ACCEPT_CHARSET (&grpc_static_mdstr_table[11])
 /* "accept-encoding" */
-#define GRPC_MDSTR_ACCEPT_ENCODING (&grpc_static_mdstr_table[10])
+#define GRPC_MDSTR_ACCEPT_ENCODING (&grpc_static_mdstr_table[12])
 /* "accept-language" */
-#define GRPC_MDSTR_ACCEPT_LANGUAGE (&grpc_static_mdstr_table[11])
+#define GRPC_MDSTR_ACCEPT_LANGUAGE (&grpc_static_mdstr_table[13])
 /* "accept-ranges" */
-#define GRPC_MDSTR_ACCEPT_RANGES (&grpc_static_mdstr_table[12])
+#define GRPC_MDSTR_ACCEPT_RANGES (&grpc_static_mdstr_table[14])
 /* "access-control-allow-origin" */
-#define GRPC_MDSTR_ACCESS_CONTROL_ALLOW_ORIGIN (&grpc_static_mdstr_table[13])
+#define GRPC_MDSTR_ACCESS_CONTROL_ALLOW_ORIGIN (&grpc_static_mdstr_table[15])
 /* "age" */
-#define GRPC_MDSTR_AGE (&grpc_static_mdstr_table[14])
+#define GRPC_MDSTR_AGE (&grpc_static_mdstr_table[16])
 /* "allow" */
-#define GRPC_MDSTR_ALLOW (&grpc_static_mdstr_table[15])
+#define GRPC_MDSTR_ALLOW (&grpc_static_mdstr_table[17])
+/* "application/grpc" */
+#define GRPC_MDSTR_APPLICATION_SLASH_GRPC (&grpc_static_mdstr_table[18])
 /* ":authority" */
-#define GRPC_MDSTR_AUTHORITY (&grpc_static_mdstr_table[16])
+#define GRPC_MDSTR_AUTHORITY (&grpc_static_mdstr_table[19])
 /* "authorization" */
-#define GRPC_MDSTR_AUTHORIZATION (&grpc_static_mdstr_table[17])
+#define GRPC_MDSTR_AUTHORIZATION (&grpc_static_mdstr_table[20])
 /* "cache-control" */
-#define GRPC_MDSTR_CACHE_CONTROL (&grpc_static_mdstr_table[18])
+#define GRPC_MDSTR_CACHE_CONTROL (&grpc_static_mdstr_table[21])
 /* "content-disposition" */
-#define GRPC_MDSTR_CONTENT_DISPOSITION (&grpc_static_mdstr_table[19])
+#define GRPC_MDSTR_CONTENT_DISPOSITION (&grpc_static_mdstr_table[22])
 /* "content-encoding" */
-#define GRPC_MDSTR_CONTENT_ENCODING (&grpc_static_mdstr_table[20])
+#define GRPC_MDSTR_CONTENT_ENCODING (&grpc_static_mdstr_table[23])
 /* "content-language" */
-#define GRPC_MDSTR_CONTENT_LANGUAGE (&grpc_static_mdstr_table[21])
+#define GRPC_MDSTR_CONTENT_LANGUAGE (&grpc_static_mdstr_table[24])
 /* "content-length" */
-#define GRPC_MDSTR_CONTENT_LENGTH (&grpc_static_mdstr_table[22])
+#define GRPC_MDSTR_CONTENT_LENGTH (&grpc_static_mdstr_table[25])
 /* "content-location" */
-#define GRPC_MDSTR_CONTENT_LOCATION (&grpc_static_mdstr_table[23])
+#define GRPC_MDSTR_CONTENT_LOCATION (&grpc_static_mdstr_table[26])
 /* "content-range" */
-#define GRPC_MDSTR_CONTENT_RANGE (&grpc_static_mdstr_table[24])
+#define GRPC_MDSTR_CONTENT_RANGE (&grpc_static_mdstr_table[27])
 /* "content-type" */
-#define GRPC_MDSTR_CONTENT_TYPE (&grpc_static_mdstr_table[25])
+#define GRPC_MDSTR_CONTENT_TYPE (&grpc_static_mdstr_table[28])
 /* "cookie" */
-#define GRPC_MDSTR_COOKIE (&grpc_static_mdstr_table[26])
+#define GRPC_MDSTR_COOKIE (&grpc_static_mdstr_table[29])
 /* "date" */
-#define GRPC_MDSTR_DATE (&grpc_static_mdstr_table[27])
+#define GRPC_MDSTR_DATE (&grpc_static_mdstr_table[30])
 /* "deflate" */
-#define GRPC_MDSTR_DEFLATE (&grpc_static_mdstr_table[28])
+#define GRPC_MDSTR_DEFLATE (&grpc_static_mdstr_table[31])
 /* "" */
-#define GRPC_MDSTR_EMPTY (&grpc_static_mdstr_table[29])
+#define GRPC_MDSTR_EMPTY (&grpc_static_mdstr_table[32])
 /* "etag" */
-#define GRPC_MDSTR_ETAG (&grpc_static_mdstr_table[30])
+#define GRPC_MDSTR_ETAG (&grpc_static_mdstr_table[33])
 /* "expect" */
-#define GRPC_MDSTR_EXPECT (&grpc_static_mdstr_table[31])
+#define GRPC_MDSTR_EXPECT (&grpc_static_mdstr_table[34])
 /* "expires" */
-#define GRPC_MDSTR_EXPIRES (&grpc_static_mdstr_table[32])
+#define GRPC_MDSTR_EXPIRES (&grpc_static_mdstr_table[35])
 /* "from" */
-#define GRPC_MDSTR_FROM (&grpc_static_mdstr_table[33])
+#define GRPC_MDSTR_FROM (&grpc_static_mdstr_table[36])
 /* "GET" */
-#define GRPC_MDSTR_GET (&grpc_static_mdstr_table[34])
+#define GRPC_MDSTR_GET (&grpc_static_mdstr_table[37])
 /* "grpc" */
-#define GRPC_MDSTR_GRPC (&grpc_static_mdstr_table[35])
+#define GRPC_MDSTR_GRPC (&grpc_static_mdstr_table[38])
 /* "grpc-accept-encoding" */
-#define GRPC_MDSTR_GRPC_ACCEPT_ENCODING (&grpc_static_mdstr_table[36])
+#define GRPC_MDSTR_GRPC_ACCEPT_ENCODING (&grpc_static_mdstr_table[39])
 /* "grpc-encoding" */
-#define GRPC_MDSTR_GRPC_ENCODING (&grpc_static_mdstr_table[37])
+#define GRPC_MDSTR_GRPC_ENCODING (&grpc_static_mdstr_table[40])
+/* "grpc-internal-encoding-request" */
+#define GRPC_MDSTR_GRPC_INTERNAL_ENCODING_REQUEST (&grpc_static_mdstr_table[41])
 /* "grpc-message" */
-#define GRPC_MDSTR_GRPC_MESSAGE (&grpc_static_mdstr_table[38])
+#define GRPC_MDSTR_GRPC_MESSAGE (&grpc_static_mdstr_table[42])
 /* "grpc-status" */
-#define GRPC_MDSTR_GRPC_STATUS (&grpc_static_mdstr_table[39])
+#define GRPC_MDSTR_GRPC_STATUS (&grpc_static_mdstr_table[43])
 /* "grpc-timeout" */
-#define GRPC_MDSTR_GRPC_TIMEOUT (&grpc_static_mdstr_table[40])
+#define GRPC_MDSTR_GRPC_TIMEOUT (&grpc_static_mdstr_table[44])
 /* "gzip" */
-#define GRPC_MDSTR_GZIP (&grpc_static_mdstr_table[41])
+#define GRPC_MDSTR_GZIP (&grpc_static_mdstr_table[45])
 /* "gzip, deflate" */
-#define GRPC_MDSTR_GZIP_COMMA_DEFLATE (&grpc_static_mdstr_table[42])
+#define GRPC_MDSTR_GZIP_COMMA_DEFLATE (&grpc_static_mdstr_table[46])
 /* "host" */
-#define GRPC_MDSTR_HOST (&grpc_static_mdstr_table[43])
+#define GRPC_MDSTR_HOST (&grpc_static_mdstr_table[47])
 /* "http" */
-#define GRPC_MDSTR_HTTP (&grpc_static_mdstr_table[44])
+#define GRPC_MDSTR_HTTP (&grpc_static_mdstr_table[48])
 /* "https" */
-#define GRPC_MDSTR_HTTPS (&grpc_static_mdstr_table[45])
+#define GRPC_MDSTR_HTTPS (&grpc_static_mdstr_table[49])
 /* "identity" */
-#define GRPC_MDSTR_IDENTITY (&grpc_static_mdstr_table[46])
+#define GRPC_MDSTR_IDENTITY (&grpc_static_mdstr_table[50])
 /* "if-match" */
-#define GRPC_MDSTR_IF_MATCH (&grpc_static_mdstr_table[47])
+#define GRPC_MDSTR_IF_MATCH (&grpc_static_mdstr_table[51])
 /* "if-modified-since" */
-#define GRPC_MDSTR_IF_MODIFIED_SINCE (&grpc_static_mdstr_table[48])
+#define GRPC_MDSTR_IF_MODIFIED_SINCE (&grpc_static_mdstr_table[52])
 /* "if-none-match" */
-#define GRPC_MDSTR_IF_NONE_MATCH (&grpc_static_mdstr_table[49])
+#define GRPC_MDSTR_IF_NONE_MATCH (&grpc_static_mdstr_table[53])
 /* "if-range" */
-#define GRPC_MDSTR_IF_RANGE (&grpc_static_mdstr_table[50])
+#define GRPC_MDSTR_IF_RANGE (&grpc_static_mdstr_table[54])
 /* "if-unmodified-since" */
-#define GRPC_MDSTR_IF_UNMODIFIED_SINCE (&grpc_static_mdstr_table[51])
+#define GRPC_MDSTR_IF_UNMODIFIED_SINCE (&grpc_static_mdstr_table[55])
 /* "last-modified" */
-#define GRPC_MDSTR_LAST_MODIFIED (&grpc_static_mdstr_table[52])
+#define GRPC_MDSTR_LAST_MODIFIED (&grpc_static_mdstr_table[56])
 /* "link" */
-#define GRPC_MDSTR_LINK (&grpc_static_mdstr_table[53])
+#define GRPC_MDSTR_LINK (&grpc_static_mdstr_table[57])
 /* "location" */
-#define GRPC_MDSTR_LOCATION (&grpc_static_mdstr_table[54])
+#define GRPC_MDSTR_LOCATION (&grpc_static_mdstr_table[58])
 /* "max-forwards" */
-#define GRPC_MDSTR_MAX_FORWARDS (&grpc_static_mdstr_table[55])
+#define GRPC_MDSTR_MAX_FORWARDS (&grpc_static_mdstr_table[59])
 /* ":method" */
-#define GRPC_MDSTR_METHOD (&grpc_static_mdstr_table[56])
+#define GRPC_MDSTR_METHOD (&grpc_static_mdstr_table[60])
 /* ":path" */
-#define GRPC_MDSTR_PATH (&grpc_static_mdstr_table[57])
+#define GRPC_MDSTR_PATH (&grpc_static_mdstr_table[61])
 /* "POST" */
-#define GRPC_MDSTR_POST (&grpc_static_mdstr_table[58])
+#define GRPC_MDSTR_POST (&grpc_static_mdstr_table[62])
 /* "proxy-authenticate" */
-#define GRPC_MDSTR_PROXY_AUTHENTICATE (&grpc_static_mdstr_table[59])
+#define GRPC_MDSTR_PROXY_AUTHENTICATE (&grpc_static_mdstr_table[63])
 /* "proxy-authorization" */
-#define GRPC_MDSTR_PROXY_AUTHORIZATION (&grpc_static_mdstr_table[60])
+#define GRPC_MDSTR_PROXY_AUTHORIZATION (&grpc_static_mdstr_table[64])
 /* "range" */
-#define GRPC_MDSTR_RANGE (&grpc_static_mdstr_table[61])
+#define GRPC_MDSTR_RANGE (&grpc_static_mdstr_table[65])
 /* "referer" */
-#define GRPC_MDSTR_REFERER (&grpc_static_mdstr_table[62])
+#define GRPC_MDSTR_REFERER (&grpc_static_mdstr_table[66])
 /* "refresh" */
-#define GRPC_MDSTR_REFRESH (&grpc_static_mdstr_table[63])
+#define GRPC_MDSTR_REFRESH (&grpc_static_mdstr_table[67])
 /* "retry-after" */
-#define GRPC_MDSTR_RETRY_AFTER (&grpc_static_mdstr_table[64])
+#define GRPC_MDSTR_RETRY_AFTER (&grpc_static_mdstr_table[68])
 /* ":scheme" */
-#define GRPC_MDSTR_SCHEME (&grpc_static_mdstr_table[65])
+#define GRPC_MDSTR_SCHEME (&grpc_static_mdstr_table[69])
 /* "server" */
-#define GRPC_MDSTR_SERVER (&grpc_static_mdstr_table[66])
+#define GRPC_MDSTR_SERVER (&grpc_static_mdstr_table[70])
 /* "set-cookie" */
-#define GRPC_MDSTR_SET_COOKIE (&grpc_static_mdstr_table[67])
+#define GRPC_MDSTR_SET_COOKIE (&grpc_static_mdstr_table[71])
 /* "/" */
-#define GRPC_MDSTR_SLASH (&grpc_static_mdstr_table[68])
+#define GRPC_MDSTR_SLASH (&grpc_static_mdstr_table[72])
 /* "/index.html" */
-#define GRPC_MDSTR_SLASH_INDEX_DOT_HTML (&grpc_static_mdstr_table[69])
+#define GRPC_MDSTR_SLASH_INDEX_DOT_HTML (&grpc_static_mdstr_table[73])
 /* ":status" */
-#define GRPC_MDSTR_STATUS (&grpc_static_mdstr_table[70])
+#define GRPC_MDSTR_STATUS (&grpc_static_mdstr_table[74])
 /* "strict-transport-security" */
-#define GRPC_MDSTR_STRICT_TRANSPORT_SECURITY (&grpc_static_mdstr_table[71])
+#define GRPC_MDSTR_STRICT_TRANSPORT_SECURITY (&grpc_static_mdstr_table[75])
 /* "te" */
-#define GRPC_MDSTR_TE (&grpc_static_mdstr_table[72])
+#define GRPC_MDSTR_TE (&grpc_static_mdstr_table[76])
 /* "trailers" */
-#define GRPC_MDSTR_TRAILERS (&grpc_static_mdstr_table[73])
+#define GRPC_MDSTR_TRAILERS (&grpc_static_mdstr_table[77])
 /* "transfer-encoding" */
-#define GRPC_MDSTR_TRANSFER_ENCODING (&grpc_static_mdstr_table[74])
+#define GRPC_MDSTR_TRANSFER_ENCODING (&grpc_static_mdstr_table[78])
 /* "user-agent" */
-#define GRPC_MDSTR_USER_AGENT (&grpc_static_mdstr_table[75])
+#define GRPC_MDSTR_USER_AGENT (&grpc_static_mdstr_table[79])
 /* "vary" */
-#define GRPC_MDSTR_VARY (&grpc_static_mdstr_table[76])
+#define GRPC_MDSTR_VARY (&grpc_static_mdstr_table[80])
 /* "via" */
-#define GRPC_MDSTR_VIA (&grpc_static_mdstr_table[77])
+#define GRPC_MDSTR_VIA (&grpc_static_mdstr_table[81])
 /* "www-authenticate" */
-#define GRPC_MDSTR_WWW_AUTHENTICATE (&grpc_static_mdstr_table[78])
+#define GRPC_MDSTR_WWW_AUTHENTICATE (&grpc_static_mdstr_table[82])
 
-#define GRPC_STATIC_MDELEM_COUNT 65
+#define GRPC_STATIC_MDELEM_COUNT 71
 extern grpc_mdelem grpc_static_mdelem_table[GRPC_STATIC_MDELEM_COUNT];
 /* "accept-charset": "" */
 #define GRPC_MDELEM_ACCEPT_CHARSET_EMPTY (&grpc_static_mdelem_table[0])
@@ -247,101 +255,114 @@ extern grpc_mdelem grpc_static_mdelem_table[GRPC_STATIC_MDELEM_COUNT];
 #define GRPC_MDELEM_CONTENT_LOCATION_EMPTY (&grpc_static_mdelem_table[16])
 /* "content-range": "" */
 #define GRPC_MDELEM_CONTENT_RANGE_EMPTY (&grpc_static_mdelem_table[17])
+/* "content-type": "application/grpc" */
+#define GRPC_MDELEM_CONTENT_TYPE_APPLICATION_SLASH_GRPC \
+  (&grpc_static_mdelem_table[18])
 /* "content-type": "" */
-#define GRPC_MDELEM_CONTENT_TYPE_EMPTY (&grpc_static_mdelem_table[18])
+#define GRPC_MDELEM_CONTENT_TYPE_EMPTY (&grpc_static_mdelem_table[19])
 /* "cookie": "" */
-#define GRPC_MDELEM_COOKIE_EMPTY (&grpc_static_mdelem_table[19])
+#define GRPC_MDELEM_COOKIE_EMPTY (&grpc_static_mdelem_table[20])
 /* "date": "" */
-#define GRPC_MDELEM_DATE_EMPTY (&grpc_static_mdelem_table[20])
+#define GRPC_MDELEM_DATE_EMPTY (&grpc_static_mdelem_table[21])
 /* "etag": "" */
-#define GRPC_MDELEM_ETAG_EMPTY (&grpc_static_mdelem_table[21])
+#define GRPC_MDELEM_ETAG_EMPTY (&grpc_static_mdelem_table[22])
 /* "expect": "" */
-#define GRPC_MDELEM_EXPECT_EMPTY (&grpc_static_mdelem_table[22])
+#define GRPC_MDELEM_EXPECT_EMPTY (&grpc_static_mdelem_table[23])
 /* "expires": "" */
-#define GRPC_MDELEM_EXPIRES_EMPTY (&grpc_static_mdelem_table[23])
+#define GRPC_MDELEM_EXPIRES_EMPTY (&grpc_static_mdelem_table[24])
 /* "from": "" */
-#define GRPC_MDELEM_FROM_EMPTY (&grpc_static_mdelem_table[24])
+#define GRPC_MDELEM_FROM_EMPTY (&grpc_static_mdelem_table[25])
+/* "grpc-encoding": "deflate" */
+#define GRPC_MDELEM_GRPC_ENCODING_DEFLATE (&grpc_static_mdelem_table[26])
+/* "grpc-encoding": "gzip" */
+#define GRPC_MDELEM_GRPC_ENCODING_GZIP (&grpc_static_mdelem_table[27])
+/* "grpc-encoding": "identity" */
+#define GRPC_MDELEM_GRPC_ENCODING_IDENTITY (&grpc_static_mdelem_table[28])
 /* "grpc-status": "0" */
-#define GRPC_MDELEM_GRPC_STATUS_0 (&grpc_static_mdelem_table[25])
+#define GRPC_MDELEM_GRPC_STATUS_0 (&grpc_static_mdelem_table[29])
+/* "grpc-status": "1" */
+#define GRPC_MDELEM_GRPC_STATUS_1 (&grpc_static_mdelem_table[30])
+/* "grpc-status": "2" */
+#define GRPC_MDELEM_GRPC_STATUS_2 (&grpc_static_mdelem_table[31])
 /* "host": "" */
-#define GRPC_MDELEM_HOST_EMPTY (&grpc_static_mdelem_table[26])
+#define GRPC_MDELEM_HOST_EMPTY (&grpc_static_mdelem_table[32])
 /* "if-match": "" */
-#define GRPC_MDELEM_IF_MATCH_EMPTY (&grpc_static_mdelem_table[27])
+#define GRPC_MDELEM_IF_MATCH_EMPTY (&grpc_static_mdelem_table[33])
 /* "if-modified-since": "" */
-#define GRPC_MDELEM_IF_MODIFIED_SINCE_EMPTY (&grpc_static_mdelem_table[28])
+#define GRPC_MDELEM_IF_MODIFIED_SINCE_EMPTY (&grpc_static_mdelem_table[34])
 /* "if-none-match": "" */
-#define GRPC_MDELEM_IF_NONE_MATCH_EMPTY (&grpc_static_mdelem_table[29])
+#define GRPC_MDELEM_IF_NONE_MATCH_EMPTY (&grpc_static_mdelem_table[35])
 /* "if-range": "" */
-#define GRPC_MDELEM_IF_RANGE_EMPTY (&grpc_static_mdelem_table[30])
+#define GRPC_MDELEM_IF_RANGE_EMPTY (&grpc_static_mdelem_table[36])
 /* "if-unmodified-since": "" */
-#define GRPC_MDELEM_IF_UNMODIFIED_SINCE_EMPTY (&grpc_static_mdelem_table[31])
+#define GRPC_MDELEM_IF_UNMODIFIED_SINCE_EMPTY (&grpc_static_mdelem_table[37])
 /* "last-modified": "" */
-#define GRPC_MDELEM_LAST_MODIFIED_EMPTY (&grpc_static_mdelem_table[32])
+#define GRPC_MDELEM_LAST_MODIFIED_EMPTY (&grpc_static_mdelem_table[38])
 /* "link": "" */
-#define GRPC_MDELEM_LINK_EMPTY (&grpc_static_mdelem_table[33])
+#define GRPC_MDELEM_LINK_EMPTY (&grpc_static_mdelem_table[39])
 /* "location": "" */
-#define GRPC_MDELEM_LOCATION_EMPTY (&grpc_static_mdelem_table[34])
+#define GRPC_MDELEM_LOCATION_EMPTY (&grpc_static_mdelem_table[40])
 /* "max-forwards": "" */
-#define GRPC_MDELEM_MAX_FORWARDS_EMPTY (&grpc_static_mdelem_table[35])
+#define GRPC_MDELEM_MAX_FORWARDS_EMPTY (&grpc_static_mdelem_table[41])
 /* ":method": "GET" */
-#define GRPC_MDELEM_METHOD_GET (&grpc_static_mdelem_table[36])
+#define GRPC_MDELEM_METHOD_GET (&grpc_static_mdelem_table[42])
 /* ":method": "POST" */
-#define GRPC_MDELEM_METHOD_POST (&grpc_static_mdelem_table[37])
+#define GRPC_MDELEM_METHOD_POST (&grpc_static_mdelem_table[43])
 /* ":path": "/" */
-#define GRPC_MDELEM_PATH_SLASH (&grpc_static_mdelem_table[38])
+#define GRPC_MDELEM_PATH_SLASH (&grpc_static_mdelem_table[44])
 /* ":path": "/index.html" */
-#define GRPC_MDELEM_PATH_SLASH_INDEX_DOT_HTML (&grpc_static_mdelem_table[39])
+#define GRPC_MDELEM_PATH_SLASH_INDEX_DOT_HTML (&grpc_static_mdelem_table[45])
 /* "proxy-authenticate": "" */
-#define GRPC_MDELEM_PROXY_AUTHENTICATE_EMPTY (&grpc_static_mdelem_table[40])
+#define GRPC_MDELEM_PROXY_AUTHENTICATE_EMPTY (&grpc_static_mdelem_table[46])
 /* "proxy-authorization": "" */
-#define GRPC_MDELEM_PROXY_AUTHORIZATION_EMPTY (&grpc_static_mdelem_table[41])
+#define GRPC_MDELEM_PROXY_AUTHORIZATION_EMPTY (&grpc_static_mdelem_table[47])
 /* "range": "" */
-#define GRPC_MDELEM_RANGE_EMPTY (&grpc_static_mdelem_table[42])
+#define GRPC_MDELEM_RANGE_EMPTY (&grpc_static_mdelem_table[48])
 /* "referer": "" */
-#define GRPC_MDELEM_REFERER_EMPTY (&grpc_static_mdelem_table[43])
+#define GRPC_MDELEM_REFERER_EMPTY (&grpc_static_mdelem_table[49])
 /* "refresh": "" */
-#define GRPC_MDELEM_REFRESH_EMPTY (&grpc_static_mdelem_table[44])
+#define GRPC_MDELEM_REFRESH_EMPTY (&grpc_static_mdelem_table[50])
 /* "retry-after": "" */
-#define GRPC_MDELEM_RETRY_AFTER_EMPTY (&grpc_static_mdelem_table[45])
+#define GRPC_MDELEM_RETRY_AFTER_EMPTY (&grpc_static_mdelem_table[51])
 /* ":scheme": "grpc" */
-#define GRPC_MDELEM_SCHEME_GRPC (&grpc_static_mdelem_table[46])
+#define GRPC_MDELEM_SCHEME_GRPC (&grpc_static_mdelem_table[52])
 /* ":scheme": "http" */
-#define GRPC_MDELEM_SCHEME_HTTP (&grpc_static_mdelem_table[47])
+#define GRPC_MDELEM_SCHEME_HTTP (&grpc_static_mdelem_table[53])
 /* ":scheme": "https" */
-#define GRPC_MDELEM_SCHEME_HTTPS (&grpc_static_mdelem_table[48])
+#define GRPC_MDELEM_SCHEME_HTTPS (&grpc_static_mdelem_table[54])
 /* "server": "" */
-#define GRPC_MDELEM_SERVER_EMPTY (&grpc_static_mdelem_table[49])
+#define GRPC_MDELEM_SERVER_EMPTY (&grpc_static_mdelem_table[55])
 /* "set-cookie": "" */
-#define GRPC_MDELEM_SET_COOKIE_EMPTY (&grpc_static_mdelem_table[50])
+#define GRPC_MDELEM_SET_COOKIE_EMPTY (&grpc_static_mdelem_table[56])
 /* ":status": "200" */
-#define GRPC_MDELEM_STATUS_200 (&grpc_static_mdelem_table[51])
+#define GRPC_MDELEM_STATUS_200 (&grpc_static_mdelem_table[57])
 /* ":status": "204" */
-#define GRPC_MDELEM_STATUS_204 (&grpc_static_mdelem_table[52])
+#define GRPC_MDELEM_STATUS_204 (&grpc_static_mdelem_table[58])
 /* ":status": "206" */
-#define GRPC_MDELEM_STATUS_206 (&grpc_static_mdelem_table[53])
+#define GRPC_MDELEM_STATUS_206 (&grpc_static_mdelem_table[59])
 /* ":status": "304" */
-#define GRPC_MDELEM_STATUS_304 (&grpc_static_mdelem_table[54])
+#define GRPC_MDELEM_STATUS_304 (&grpc_static_mdelem_table[60])
 /* ":status": "400" */
-#define GRPC_MDELEM_STATUS_400 (&grpc_static_mdelem_table[55])
+#define GRPC_MDELEM_STATUS_400 (&grpc_static_mdelem_table[61])
 /* ":status": "404" */
-#define GRPC_MDELEM_STATUS_404 (&grpc_static_mdelem_table[56])
+#define GRPC_MDELEM_STATUS_404 (&grpc_static_mdelem_table[62])
 /* ":status": "500" */
-#define GRPC_MDELEM_STATUS_500 (&grpc_static_mdelem_table[57])
+#define GRPC_MDELEM_STATUS_500 (&grpc_static_mdelem_table[63])
 /* "strict-transport-security": "" */
 #define GRPC_MDELEM_STRICT_TRANSPORT_SECURITY_EMPTY \
-  (&grpc_static_mdelem_table[58])
+  (&grpc_static_mdelem_table[64])
 /* "te": "trailers" */
-#define GRPC_MDELEM_TE_TRAILERS (&grpc_static_mdelem_table[59])
+#define GRPC_MDELEM_TE_TRAILERS (&grpc_static_mdelem_table[65])
 /* "transfer-encoding": "" */
-#define GRPC_MDELEM_TRANSFER_ENCODING_EMPTY (&grpc_static_mdelem_table[60])
+#define GRPC_MDELEM_TRANSFER_ENCODING_EMPTY (&grpc_static_mdelem_table[66])
 /* "user-agent": "" */
-#define GRPC_MDELEM_USER_AGENT_EMPTY (&grpc_static_mdelem_table[61])
+#define GRPC_MDELEM_USER_AGENT_EMPTY (&grpc_static_mdelem_table[67])
 /* "vary": "" */
-#define GRPC_MDELEM_VARY_EMPTY (&grpc_static_mdelem_table[62])
+#define GRPC_MDELEM_VARY_EMPTY (&grpc_static_mdelem_table[68])
 /* "via": "" */
-#define GRPC_MDELEM_VIA_EMPTY (&grpc_static_mdelem_table[63])
+#define GRPC_MDELEM_VIA_EMPTY (&grpc_static_mdelem_table[69])
 /* "www-authenticate": "" */
-#define GRPC_MDELEM_WWW_AUTHENTICATE_EMPTY (&grpc_static_mdelem_table[64])
+#define GRPC_MDELEM_WWW_AUTHENTICATE_EMPTY (&grpc_static_mdelem_table[70])
 
 const gpr_uint8 grpc_static_metadata_elem_indices[GRPC_STATIC_MDELEM_COUNT * 2];
 const char *const grpc_static_metadata_strings[GRPC_STATIC_MDSTR_COUNT];