Initial checkin of gRPC to third_party/

third_party/grpc/src/core/transport/chttp2/hpack_encoder.c

Index: third_party/grpc/src/core/transport/chttp2/hpack_encoder.c
diff --git a/third_party/grpc/src/core/transport/chttp2/hpack_encoder.c b/third_party/grpc/src/core/transport/chttp2/hpack_encoder.c
new file mode 100644
index 0000000000000000000000000000000000000000..f30f574d0635c9fc3e7ba445f4fc5edb789b6b1a
--- /dev/null
+++ b/third_party/grpc/src/core/transport/chttp2/hpack_encoder.c
@@ -0,0 +1,568 @@
+/*
+ *
+ * Copyright 2015-2016, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#include "src/core/transport/chttp2/hpack_encoder.h"
+
+#include <assert.h>
+#include <string.h>
+
+/* This is here for grpc_is_binary_header
+ * TODO(murgatroid99): Remove this
+ */
+#include <grpc/grpc.h>
+
+#include <grpc/support/alloc.h>
+#include <grpc/support/log.h>
+#include <grpc/support/useful.h>
+
+#include "src/core/transport/chttp2/bin_encoder.h"
+#include "src/core/transport/chttp2/hpack_table.h"
+#include "src/core/transport/chttp2/timeout_encoding.h"
+#include "src/core/transport/chttp2/varint.h"
+#include "src/core/transport/static_metadata.h"
+
+#define HASH_FRAGMENT_1(x) ((x)&255)
+#define HASH_FRAGMENT_2(x) ((x >> 8) & 255)
+#define HASH_FRAGMENT_3(x) ((x >> 16) & 255)
+#define HASH_FRAGMENT_4(x) ((x >> 24) & 255)
+
+/* if the probability of this item being seen again is < 1/x then don't add
+   it to the table */
+#define ONE_ON_ADD_PROBABILITY 128
+/* don't consider adding anything bigger than this to the hpack table */
+#define MAX_DECODER_SPACE_USAGE 512
+
+typedef struct {
+  int is_first_frame;
+  /* number of bytes in 'output' when we started the frame - used to calculate
+     frame length */
+  size_t output_length_at_start_of_frame;
+  /* index (in output) of the header for the current frame */
+  size_t header_idx;
+  /* have we seen a regular (non-colon-prefixed) header yet? */
+  uint8_t seen_regular_header;
+  /* output stream id */
+  uint32_t stream_id;
+  gpr_slice_buffer *output;
+} framer_state;
+
+/* fills p (which is expected to be 9 bytes long) with a data frame header */
+static void fill_header(uint8_t *p, uint8_t type, uint32_t id, size_t len,
+                        uint8_t flags) {
+  GPR_ASSERT(len < 16777316);
+  *p++ = (uint8_t)(len >> 16);
+  *p++ = (uint8_t)(len >> 8);
+  *p++ = (uint8_t)(len);
+  *p++ = type;
+  *p++ = flags;
+  *p++ = (uint8_t)(id >> 24);
+  *p++ = (uint8_t)(id >> 16);
+  *p++ = (uint8_t)(id >> 8);
+  *p++ = (uint8_t)(id);
+}
+
+/* finish a frame - fill in the previously reserved header */
+static void finish_frame(framer_state *st, int is_header_boundary,
+                         int is_last_in_stream) {
+  uint8_t type = 0xff;
+  type = st->is_first_frame ? GRPC_CHTTP2_FRAME_HEADER
+                            : GRPC_CHTTP2_FRAME_CONTINUATION;
+  fill_header(
+      GPR_SLICE_START_PTR(st->output->slices[st->header_idx]), type,
+      st->stream_id, st->output->length - st->output_length_at_start_of_frame,
+      (uint8_t)((is_last_in_stream ? GRPC_CHTTP2_DATA_FLAG_END_STREAM : 0) |
+                (is_header_boundary ? GRPC_CHTTP2_DATA_FLAG_END_HEADERS : 0)));
+  st->is_first_frame = 0;
+}
+
+/* begin a new frame: reserve off header space, remember how many bytes we'd
+   output before beginning */
+static void begin_frame(framer_state *st) {
+  st->header_idx =
+      gpr_slice_buffer_add_indexed(st->output, gpr_slice_malloc(9));
+  st->output_length_at_start_of_frame = st->output->length;
+}
+
+/* make sure that the current frame is of the type desired, and has sufficient
+   space to add at least about_to_add bytes -- finishes the current frame if
+   needed */
+static void ensure_space(framer_state *st, size_t need_bytes) {
+  if (st->output->length - st->output_length_at_start_of_frame + need_bytes <=
+      GRPC_CHTTP2_MAX_PAYLOAD_LENGTH) {
+    return;
+  }
+  finish_frame(st, 0, 0);
+  begin_frame(st);
+}
+
+/* increment a filter count, halve all counts if one element reaches max */
+static void inc_filter(uint8_t idx, uint32_t *sum, uint8_t *elems) {
+  elems[idx]++;
+  if (elems[idx] < 255) {
+    (*sum)++;
+  } else {
+    int i;
+    *sum = 0;
+    for (i = 0; i < GRPC_CHTTP2_HPACKC_NUM_FILTERS; i++) {
+      elems[i] /= 2;
+      (*sum) += elems[i];
+    }
+  }
+}
+
+static void add_header_data(framer_state *st, gpr_slice slice) {
+  size_t len = GPR_SLICE_LENGTH(slice);
+  size_t remaining;
+  if (len == 0) return;
+  remaining = GRPC_CHTTP2_MAX_PAYLOAD_LENGTH +
+              st->output_length_at_start_of_frame - st->output->length;
+  if (len <= remaining) {
+    gpr_slice_buffer_add(st->output, slice);
+  } else {
+    gpr_slice_buffer_add(st->output, gpr_slice_split_head(&slice, remaining));
+    finish_frame(st, 0, 0);
+    begin_frame(st);
+    add_header_data(st, slice);
+  }
+}
+
+static uint8_t *add_tiny_header_data(framer_state *st, size_t len) {
+  ensure_space(st, len);
+  return gpr_slice_buffer_tiny_add(st->output, len);
+}
+
+static void evict_entry(grpc_chttp2_hpack_compressor *c) {
+  c->tail_remote_index++;
+  GPR_ASSERT(c->tail_remote_index > 0);
+  GPR_ASSERT(c->table_size >=
+             c->table_elem_size[c->tail_remote_index % c->cap_table_elems]);
+  GPR_ASSERT(c->table_elems > 0);
+  c->table_size =
+      (uint16_t)(c->table_size -
+                 c->table_elem_size[c->tail_remote_index % c->cap_table_elems]);
+  c->table_elems--;
+}
+
+/* add an element to the decoder table */
+static void add_elem(grpc_chttp2_hpack_compressor *c, grpc_mdelem *elem) {
+  uint32_t key_hash = elem->key->hash;
+  uint32_t elem_hash = GRPC_MDSTR_KV_HASH(key_hash, elem->value->hash);
+  uint32_t new_index = c->tail_remote_index + c->table_elems + 1;
+  size_t elem_size = 32 + GPR_SLICE_LENGTH(elem->key->slice) +
+                     GPR_SLICE_LENGTH(elem->value->slice);
+
+  GPR_ASSERT(elem_size < 65536);
+
+  if (elem_size > c->max_table_size) {
+    while (c->table_size > 0) {
+      evict_entry(c);
+    }
+    return;
+  }
+
+  /* Reserve space for this element in the remote table: if this overflows
+     the current table, drop elements until it fits, matching the decompressor
+     algorithm */
+  while (c->table_size + elem_size > c->max_table_size) {
+    evict_entry(c);
+  }
+  GPR_ASSERT(c->table_elems < c->max_table_size);
+  c->table_elem_size[new_index % c->cap_table_elems] = (uint16_t)elem_size;
+  c->table_size = (uint16_t)(c->table_size + elem_size);
+  c->table_elems++;
+
+  /* Store this element into {entries,indices}_elem */
+  if (c->entries_elems[HASH_FRAGMENT_2(elem_hash)] == elem) {
+    /* already there: update with new index */
+    c->indices_elems[HASH_FRAGMENT_2(elem_hash)] = new_index;
+  } else if (c->entries_elems[HASH_FRAGMENT_3(elem_hash)] == elem) {
+    /* already there (cuckoo): update with new index */
+    c->indices_elems[HASH_FRAGMENT_3(elem_hash)] = new_index;
+  } else if (c->entries_elems[HASH_FRAGMENT_2(elem_hash)] == NULL) {
+    /* not there, but a free element: add */
+    c->entries_elems[HASH_FRAGMENT_2(elem_hash)] = GRPC_MDELEM_REF(elem);
+    c->indices_elems[HASH_FRAGMENT_2(elem_hash)] = new_index;
+  } else if (c->entries_elems[HASH_FRAGMENT_3(elem_hash)] == NULL) {
+    /* not there (cuckoo), but a free element: add */
+    c->entries_elems[HASH_FRAGMENT_3(elem_hash)] = GRPC_MDELEM_REF(elem);
+    c->indices_elems[HASH_FRAGMENT_3(elem_hash)] = new_index;
+  } else if (c->indices_elems[HASH_FRAGMENT_2(elem_hash)] <
+             c->indices_elems[HASH_FRAGMENT_3(elem_hash)]) {
+    /* not there: replace oldest */
+    GRPC_MDELEM_UNREF(c->entries_elems[HASH_FRAGMENT_2(elem_hash)]);
+    c->entries_elems[HASH_FRAGMENT_2(elem_hash)] = GRPC_MDELEM_REF(elem);
+    c->indices_elems[HASH_FRAGMENT_2(elem_hash)] = new_index;
+  } else {
+    /* not there: replace oldest */
+    GRPC_MDELEM_UNREF(c->entries_elems[HASH_FRAGMENT_3(elem_hash)]);
+    c->entries_elems[HASH_FRAGMENT_3(elem_hash)] = GRPC_MDELEM_REF(elem);
+    c->indices_elems[HASH_FRAGMENT_3(elem_hash)] = new_index;
+  }
+
+  /* do exactly the same for the key (so we can find by that again too) */
+
+  if (c->entries_keys[HASH_FRAGMENT_2(key_hash)] == elem->key) {
+    c->indices_keys[HASH_FRAGMENT_2(key_hash)] = new_index;
+  } else if (c->entries_keys[HASH_FRAGMENT_3(key_hash)] == elem->key) {
+    c->indices_keys[HASH_FRAGMENT_3(key_hash)] = new_index;
+  } else if (c->entries_keys[HASH_FRAGMENT_2(key_hash)] == NULL) {
+    c->entries_keys[HASH_FRAGMENT_2(key_hash)] = GRPC_MDSTR_REF(elem->key);
+    c->indices_keys[HASH_FRAGMENT_2(key_hash)] = new_index;
+  } else if (c->entries_keys[HASH_FRAGMENT_3(key_hash)] == NULL) {
+    c->entries_keys[HASH_FRAGMENT_3(key_hash)] = GRPC_MDSTR_REF(elem->key);
+    c->indices_keys[HASH_FRAGMENT_3(key_hash)] = new_index;
+  } else if (c->indices_keys[HASH_FRAGMENT_2(key_hash)] <
+             c->indices_keys[HASH_FRAGMENT_3(key_hash)]) {
+    GRPC_MDSTR_UNREF(c->entries_keys[HASH_FRAGMENT_2(key_hash)]);
+    c->entries_keys[HASH_FRAGMENT_2(key_hash)] = GRPC_MDSTR_REF(elem->key);
+    c->indices_keys[HASH_FRAGMENT_2(key_hash)] = new_index;
+  } else {
+    GRPC_MDSTR_UNREF(c->entries_keys[HASH_FRAGMENT_3(key_hash)]);
+    c->entries_keys[HASH_FRAGMENT_3(key_hash)] = GRPC_MDSTR_REF(elem->key);
+    c->indices_keys[HASH_FRAGMENT_3(key_hash)] = new_index;
+  }
+}
+
+static void emit_indexed(grpc_chttp2_hpack_compressor *c, uint32_t elem_index,
+                         framer_state *st) {
+  uint32_t len = GRPC_CHTTP2_VARINT_LENGTH(elem_index, 1);
+  GRPC_CHTTP2_WRITE_VARINT(elem_index, 1, 0x80, add_tiny_header_data(st, len),
+                           len);
+}
+
+static gpr_slice get_wire_value(grpc_mdelem *elem, uint8_t *huffman_prefix) {
+  if (grpc_is_binary_header((const char *)GPR_SLICE_START_PTR(elem->key->slice),
+                            GPR_SLICE_LENGTH(elem->key->slice))) {
+    *huffman_prefix = 0x80;
+    return grpc_mdstr_as_base64_encoded_and_huffman_compressed(elem->value);
+  }
+  /* TODO(ctiller): opportunistically compress non-binary headers */
+  *huffman_prefix = 0x00;
+  return elem->value->slice;
+}
+
+static void emit_lithdr_incidx(grpc_chttp2_hpack_compressor *c,
+                               uint32_t key_index, grpc_mdelem *elem,
+                               framer_state *st) {
+  uint32_t len_pfx = GRPC_CHTTP2_VARINT_LENGTH(key_index, 2);
+  uint8_t huffman_prefix;
+  gpr_slice value_slice = get_wire_value(elem, &huffman_prefix);
+  size_t len_val = GPR_SLICE_LENGTH(value_slice);
+  uint32_t len_val_len;
+  GPR_ASSERT(len_val <= UINT32_MAX);
+  len_val_len = GRPC_CHTTP2_VARINT_LENGTH((uint32_t)len_val, 1);
+  GRPC_CHTTP2_WRITE_VARINT(key_index, 2, 0x40,
+                           add_tiny_header_data(st, len_pfx), len_pfx);
+  GRPC_CHTTP2_WRITE_VARINT((uint32_t)len_val, 1, huffman_prefix,
+                           add_tiny_header_data(st, len_val_len), len_val_len);
+  add_header_data(st, gpr_slice_ref(value_slice));
+}
+
+static void emit_lithdr_noidx(grpc_chttp2_hpack_compressor *c,
+                              uint32_t key_index, grpc_mdelem *elem,
+                              framer_state *st) {
+  uint32_t len_pfx = GRPC_CHTTP2_VARINT_LENGTH(key_index, 4);
+  uint8_t huffman_prefix;
+  gpr_slice value_slice = get_wire_value(elem, &huffman_prefix);
+  size_t len_val = GPR_SLICE_LENGTH(value_slice);
+  uint32_t len_val_len;
+  GPR_ASSERT(len_val <= UINT32_MAX);
+  len_val_len = GRPC_CHTTP2_VARINT_LENGTH((uint32_t)len_val, 1);
+  GRPC_CHTTP2_WRITE_VARINT(key_index, 4, 0x00,
+                           add_tiny_header_data(st, len_pfx), len_pfx);
+  GRPC_CHTTP2_WRITE_VARINT((uint32_t)len_val, 1, huffman_prefix,
+                           add_tiny_header_data(st, len_val_len), len_val_len);
+  add_header_data(st, gpr_slice_ref(value_slice));
+}
+
+static void emit_lithdr_incidx_v(grpc_chttp2_hpack_compressor *c,
+                                 grpc_mdelem *elem, framer_state *st) {
+  uint32_t len_key = (uint32_t)GPR_SLICE_LENGTH(elem->key->slice);
+  uint8_t huffman_prefix;
+  gpr_slice value_slice = get_wire_value(elem, &huffman_prefix);
+  uint32_t len_val = (uint32_t)GPR_SLICE_LENGTH(value_slice);
+  uint32_t len_key_len = GRPC_CHTTP2_VARINT_LENGTH(len_key, 1);
+  uint32_t len_val_len = GRPC_CHTTP2_VARINT_LENGTH(len_val, 1);
+  GPR_ASSERT(len_key <= UINT32_MAX);
+  GPR_ASSERT(GPR_SLICE_LENGTH(value_slice) <= UINT32_MAX);
+  *add_tiny_header_data(st, 1) = 0x40;
+  GRPC_CHTTP2_WRITE_VARINT(len_key, 1, 0x00,
+                           add_tiny_header_data(st, len_key_len), len_key_len);
+  add_header_data(st, gpr_slice_ref(elem->key->slice));
+  GRPC_CHTTP2_WRITE_VARINT(len_val, 1, huffman_prefix,
+                           add_tiny_header_data(st, len_val_len), len_val_len);
+  add_header_data(st, gpr_slice_ref(value_slice));
+}
+
+static void emit_lithdr_noidx_v(grpc_chttp2_hpack_compressor *c,
+                                grpc_mdelem *elem, framer_state *st) {
+  uint32_t len_key = (uint32_t)GPR_SLICE_LENGTH(elem->key->slice);
+  uint8_t huffman_prefix;
+  gpr_slice value_slice = get_wire_value(elem, &huffman_prefix);
+  uint32_t len_val = (uint32_t)GPR_SLICE_LENGTH(value_slice);
+  uint32_t len_key_len = GRPC_CHTTP2_VARINT_LENGTH(len_key, 1);
+  uint32_t len_val_len = GRPC_CHTTP2_VARINT_LENGTH(len_val, 1);
+  GPR_ASSERT(len_key <= UINT32_MAX);
+  GPR_ASSERT(GPR_SLICE_LENGTH(value_slice) <= UINT32_MAX);
+  *add_tiny_header_data(st, 1) = 0x00;
+  GRPC_CHTTP2_WRITE_VARINT(len_key, 1, 0x00,
+                           add_tiny_header_data(st, len_key_len), len_key_len);
+  add_header_data(st, gpr_slice_ref(elem->key->slice));
+  GRPC_CHTTP2_WRITE_VARINT(len_val, 1, huffman_prefix,
+                           add_tiny_header_data(st, len_val_len), len_val_len);
+  add_header_data(st, gpr_slice_ref(value_slice));
+}
+
+static void emit_advertise_table_size_change(grpc_chttp2_hpack_compressor *c,
+                                             framer_state *st) {
+  uint32_t len = GRPC_CHTTP2_VARINT_LENGTH(c->max_table_size, 3);
+  GRPC_CHTTP2_WRITE_VARINT(c->max_table_size, 3, 0x20,
+                           add_tiny_header_data(st, len), len);
+  c->advertise_table_size_change = 0;
+}
+
+static uint32_t dynidx(grpc_chttp2_hpack_compressor *c, uint32_t elem_index) {
+  return 1 + GRPC_CHTTP2_LAST_STATIC_ENTRY + c->tail_remote_index +
+         c->table_elems - elem_index;
+}
+
+/* encode an mdelem */
+static void hpack_enc(grpc_chttp2_hpack_compressor *c, grpc_mdelem *elem,
+                      framer_state *st) {
+  uint32_t key_hash = elem->key->hash;
+  uint32_t elem_hash = GRPC_MDSTR_KV_HASH(key_hash, elem->value->hash);
+  size_t decoder_space_usage;
+  uint32_t indices_key;
+  int should_add_elem;
+
+  GPR_ASSERT(GPR_SLICE_LENGTH(elem->key->slice) > 0);
+  if (GPR_SLICE_START_PTR(elem->key->slice)[0] != ':') { /* regular header */
+    st->seen_regular_header = 1;
+  } else {
+    GPR_ASSERT(
+        st->seen_regular_header == 0 &&
+        "Reserved header (colon-prefixed) happening after regular ones.");
+  }
+
+  inc_filter(HASH_FRAGMENT_1(elem_hash), &c->filter_elems_sum, c->filter_elems);
+
+  /* is this elem currently in the decoders table? */
+
+  if (c->entries_elems[HASH_FRAGMENT_2(elem_hash)] == elem &&
+      c->indices_elems[HASH_FRAGMENT_2(elem_hash)] > c->tail_remote_index) {
+    /* HIT: complete element (first cuckoo hash) */
+    emit_indexed(c, dynidx(c, c->indices_elems[HASH_FRAGMENT_2(elem_hash)]),
+                 st);
+    return;
+  }
+
+  if (c->entries_elems[HASH_FRAGMENT_3(elem_hash)] == elem &&
+      c->indices_elems[HASH_FRAGMENT_3(elem_hash)] > c->tail_remote_index) {
+    /* HIT: complete element (second cuckoo hash) */
+    emit_indexed(c, dynidx(c, c->indices_elems[HASH_FRAGMENT_3(elem_hash)]),
+                 st);
+    return;
+  }
+
+  /* should this elem be in the table? */
+  decoder_space_usage = 32 + GPR_SLICE_LENGTH(elem->key->slice) +
+                        GPR_SLICE_LENGTH(elem->value->slice);
+  should_add_elem = decoder_space_usage < MAX_DECODER_SPACE_USAGE &&
+                    c->filter_elems[HASH_FRAGMENT_1(elem_hash)] >=
+                        c->filter_elems_sum / ONE_ON_ADD_PROBABILITY;
+
+  /* no hits for the elem... maybe there's a key? */
+
+  indices_key = c->indices_keys[HASH_FRAGMENT_2(key_hash)];
+  if (c->entries_keys[HASH_FRAGMENT_2(key_hash)] == elem->key &&
+      indices_key > c->tail_remote_index) {
+    /* HIT: key (first cuckoo hash) */
+    if (should_add_elem) {
+      emit_lithdr_incidx(c, dynidx(c, indices_key), elem, st);
+      add_elem(c, elem);
+      return;
+    } else {
+      emit_lithdr_noidx(c, dynidx(c, indices_key), elem, st);
+      return;
+    }
+    GPR_UNREACHABLE_CODE(return );
+  }
+
+  indices_key = c->indices_keys[HASH_FRAGMENT_3(key_hash)];
+  if (c->entries_keys[HASH_FRAGMENT_3(key_hash)] == elem->key &&
+      indices_key > c->tail_remote_index) {
+    /* HIT: key (first cuckoo hash) */
+    if (should_add_elem) {
+      emit_lithdr_incidx(c, dynidx(c, indices_key), elem, st);
+      add_elem(c, elem);
+      return;
+    } else {
+      emit_lithdr_noidx(c, dynidx(c, indices_key), elem, st);
+      return;
+    }
+    GPR_UNREACHABLE_CODE(return );
+  }
+
+  /* no elem, key in the table... fall back to literal emission */
+
+  if (should_add_elem) {
+    emit_lithdr_incidx_v(c, elem, st);
+    add_elem(c, elem);
+    return;
+  } else {
+    emit_lithdr_noidx_v(c, elem, st);
+    return;
+  }
+  GPR_UNREACHABLE_CODE(return );
+}
+
+#define STRLEN_LIT(x) (sizeof(x) - 1)
+#define TIMEOUT_KEY "grpc-timeout"
+
+static void deadline_enc(grpc_chttp2_hpack_compressor *c, gpr_timespec deadline,
+                         framer_state *st) {
+  char timeout_str[GRPC_CHTTP2_TIMEOUT_ENCODE_MIN_BUFSIZE];
+  grpc_mdelem *mdelem;
+  grpc_chttp2_encode_timeout(
+      gpr_time_sub(deadline, gpr_now(deadline.clock_type)), timeout_str);
+  mdelem = grpc_mdelem_from_metadata_strings(
+      GRPC_MDSTR_GRPC_TIMEOUT, grpc_mdstr_from_string(timeout_str));
+  hpack_enc(c, mdelem, st);
+  GRPC_MDELEM_UNREF(mdelem);
+}
+
+static uint32_t elems_for_bytes(uint32_t bytes) { return (bytes + 31) / 32; }
+
+void grpc_chttp2_hpack_compressor_init(grpc_chttp2_hpack_compressor *c) {
+  memset(c, 0, sizeof(*c));
+  c->max_table_size = GRPC_CHTTP2_HPACKC_INITIAL_TABLE_SIZE;
+  c->cap_table_elems = elems_for_bytes(c->max_table_size);
+  c->max_table_elems = c->cap_table_elems;
+  c->max_usable_size = GRPC_CHTTP2_HPACKC_INITIAL_TABLE_SIZE;
+  c->table_elem_size =
+      gpr_malloc(sizeof(*c->table_elem_size) * c->cap_table_elems);
+  memset(c->table_elem_size, 0,
+         sizeof(*c->table_elem_size) * c->cap_table_elems);
+}
+
+void grpc_chttp2_hpack_compressor_destroy(grpc_chttp2_hpack_compressor *c) {
+  int i;
+  for (i = 0; i < GRPC_CHTTP2_HPACKC_NUM_VALUES; i++) {
+    if (c->entries_keys[i]) GRPC_MDSTR_UNREF(c->entries_keys[i]);
+    if (c->entries_elems[i]) GRPC_MDELEM_UNREF(c->entries_elems[i]);
+  }
+  gpr_free(c->table_elem_size);
+}
+
+void grpc_chttp2_hpack_compressor_set_max_usable_size(
+    grpc_chttp2_hpack_compressor *c, uint32_t max_table_size) {
+  c->max_usable_size = max_table_size;
+  grpc_chttp2_hpack_compressor_set_max_table_size(
+      c, GPR_MIN(c->max_table_size, max_table_size));
+}
+
+static void rebuild_elems(grpc_chttp2_hpack_compressor *c, uint32_t new_cap) {
+  uint16_t *table_elem_size = gpr_malloc(sizeof(*table_elem_size) * new_cap);
+  uint32_t i;
+
+  memset(table_elem_size, 0, sizeof(*table_elem_size) * new_cap);
+  GPR_ASSERT(c->table_elems <= new_cap);
+
+  for (i = 0; i < c->table_elems; i++) {
+    uint32_t ofs = c->tail_remote_index + i + 1;
+    table_elem_size[ofs % new_cap] =
+        c->table_elem_size[ofs % c->cap_table_elems];
+  }
+
+  c->cap_table_elems = new_cap;
+  gpr_free(c->table_elem_size);
+  c->table_elem_size = table_elem_size;
+}
+
+void grpc_chttp2_hpack_compressor_set_max_table_size(
+    grpc_chttp2_hpack_compressor *c, uint32_t max_table_size) {
+  max_table_size = GPR_MIN(max_table_size, c->max_usable_size);
+  if (max_table_size == c->max_table_size) {
+    return;
+  }
+  while (c->table_size > 0 && c->table_size > max_table_size) {
+    evict_entry(c);
+  }
+  c->max_table_size = max_table_size;
+  c->max_table_elems = elems_for_bytes(max_table_size);
+  if (c->max_table_elems > c->cap_table_elems) {
+    rebuild_elems(c, GPR_MAX(c->max_table_elems, 2 * c->cap_table_elems));
+  } else if (c->max_table_elems < c->cap_table_elems / 3) {
+    uint32_t new_cap = GPR_MAX(c->max_table_elems, 16);
+    if (new_cap != c->cap_table_elems) {
+      rebuild_elems(c, new_cap);
+    }
+  }
+  c->advertise_table_size_change = 1;
+  gpr_log(GPR_DEBUG, "set max table size from encoder to %d", max_table_size);
+}
+
+void grpc_chttp2_encode_header(grpc_chttp2_hpack_compressor *c,
+                               uint32_t stream_id,
+                               grpc_metadata_batch *metadata, int is_eof,
+                               gpr_slice_buffer *outbuf) {
+  framer_state st;
+  grpc_linked_mdelem *l;
+  gpr_timespec deadline;
+
+  GPR_ASSERT(stream_id != 0);
+
+  st.seen_regular_header = 0;
+  st.stream_id = stream_id;
+  st.output = outbuf;
+  st.is_first_frame = 1;
+
+  /* Encode a metadata batch; store the returned values, representing
+     a metadata element that needs to be unreffed back into the metadata
+     slot. THIS MAY NOT BE THE SAME ELEMENT (if a decoder table slot got
+     updated). After this loop, we'll do a batch unref of elements. */
+  begin_frame(&st);
+  if (c->advertise_table_size_change != 0) {
+    emit_advertise_table_size_change(c, &st);
+  }
+  grpc_metadata_batch_assert_ok(metadata);
+  for (l = metadata->list.head; l; l = l->next) {
+    hpack_enc(c, l->md, &st);
+  }
+  deadline = metadata->deadline;
+  if (gpr_time_cmp(deadline, gpr_inf_future(deadline.clock_type)) != 0) {
+    deadline_enc(c, deadline, &st);
+  }
+
+  finish_frame(&st, 1, is_eof);
+}