1 files changed, 283 insertions, 0 deletions
diff --git a/src/core/lib/compression/compression.cc b/src/core/lib/compression/compression.cc
new file mode 100644
index 0000000000..1cfac23129
--- /dev/null
+++ b/src/core/lib/compression/compression.cc
@@ -0,0 +1,283 @@
+/*
+ *
+ * Copyright 2015 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+#include <stdlib.h>
+#include <string.h>
+
+#include <grpc/compression.h>
+#include <grpc/support/useful.h>
+
+#include "src/core/lib/compression/algorithm_metadata.h"
+#include "src/core/lib/surface/api_trace.h"
+#include "src/core/lib/transport/static_metadata.h"
+
+int grpc_compression_algorithm_parse(grpc_slice name,
+                                     grpc_compression_algorithm *algorithm) {
+  /* we use strncmp not only because it's safer (even though in this case it
+   * doesn't matter, given that we are comparing against string literals, but
+   * because this way we needn't have "name" nil-terminated (useful for slice
+   * data, for example) */
+  if (grpc_slice_eq(name, GRPC_MDSTR_IDENTITY)) {
+    *algorithm = GRPC_COMPRESS_NONE;
+    return 1;
+  } else if (grpc_slice_eq(name, GRPC_MDSTR_GZIP)) {
+    *algorithm = GRPC_COMPRESS_GZIP;
+    return 1;
+  } else if (grpc_slice_eq(name, GRPC_MDSTR_DEFLATE)) {
+    *algorithm = GRPC_COMPRESS_DEFLATE;
+    return 1;
+  } else {
+    return 0;
+  }
+}
+
+int grpc_stream_compression_algorithm_parse(
+    grpc_slice name, grpc_stream_compression_algorithm *algorithm) {
+  if (grpc_slice_eq(name, GRPC_MDSTR_IDENTITY)) {
+    *algorithm = GRPC_STREAM_COMPRESS_NONE;
+    return 1;
+  } else if (grpc_slice_eq(name, GRPC_MDSTR_GZIP)) {
+    *algorithm = GRPC_STREAM_COMPRESS_GZIP;
+    return 1;
+  } else {
+    return 0;
+  }
+}
+
+int grpc_compression_algorithm_name(grpc_compression_algorithm algorithm,
+                                    const char **name) {
+  GRPC_API_TRACE("grpc_compression_algorithm_parse(algorithm=%d, name=%p)", 2,
+                 ((int)algorithm, name));
+  switch (algorithm) {
+    case GRPC_COMPRESS_NONE:
+      *name = "identity";
+      return 1;
+    case GRPC_COMPRESS_DEFLATE:
+      *name = "deflate";
+      return 1;
+    case GRPC_COMPRESS_GZIP:
+      *name = "gzip";
+      return 1;
+    case GRPC_COMPRESS_ALGORITHMS_COUNT:
+      return 0;
+  }
+  return 0;
+}
+
+int grpc_stream_compression_algorithm_name(
+    grpc_stream_compression_algorithm algorithm, const char **name) {
+  GRPC_API_TRACE(
+      "grpc_stream_compression_algorithm_parse(algorithm=%d, name=%p)", 2,
+      ((int)algorithm, name));
+  switch (algorithm) {
+    case GRPC_STREAM_COMPRESS_NONE:
+      *name = "identity";
+      return 1;
+    case GRPC_STREAM_COMPRESS_GZIP:
+      *name = "gzip";
+      return 1;
+    case GRPC_STREAM_COMPRESS_ALGORITHMS_COUNT:
+      return 0;
+  }
+  return 0;
+}
+
+grpc_compression_algorithm grpc_compression_algorithm_from_slice(
+    grpc_slice str) {
+  if (grpc_slice_eq(str, GRPC_MDSTR_IDENTITY)) return GRPC_COMPRESS_NONE;
+  if (grpc_slice_eq(str, GRPC_MDSTR_DEFLATE)) return GRPC_COMPRESS_DEFLATE;
+  if (grpc_slice_eq(str, GRPC_MDSTR_GZIP)) return GRPC_COMPRESS_GZIP;
+  return GRPC_COMPRESS_ALGORITHMS_COUNT;
+}
+
+grpc_stream_compression_algorithm grpc_stream_compression_algorithm_from_slice(
+    grpc_slice str) {
+  if (grpc_slice_eq(str, GRPC_MDSTR_IDENTITY)) return GRPC_STREAM_COMPRESS_NONE;
+  if (grpc_slice_eq(str, GRPC_MDSTR_GZIP)) return GRPC_STREAM_COMPRESS_GZIP;
+  return GRPC_STREAM_COMPRESS_ALGORITHMS_COUNT;
+}
+
+grpc_slice grpc_compression_algorithm_slice(
+    grpc_compression_algorithm algorithm) {
+  switch (algorithm) {
+    case GRPC_COMPRESS_NONE:
+      return GRPC_MDSTR_IDENTITY;
+    case GRPC_COMPRESS_DEFLATE:
+      return GRPC_MDSTR_DEFLATE;
+    case GRPC_COMPRESS_GZIP:
+      return GRPC_MDSTR_GZIP;
+    case GRPC_COMPRESS_ALGORITHMS_COUNT:
+      return grpc_empty_slice();
+  }
+  return grpc_empty_slice();
+}
+
+grpc_slice grpc_stream_compression_algorithm_slice(
+    grpc_stream_compression_algorithm algorithm) {
+  switch (algorithm) {
+    case GRPC_STREAM_COMPRESS_NONE:
+      return GRPC_MDSTR_IDENTITY;
+    case GRPC_STREAM_COMPRESS_GZIP:
+      return GRPC_MDSTR_GZIP;
+    case GRPC_STREAM_COMPRESS_ALGORITHMS_COUNT:
+      return grpc_empty_slice();
+  }
+  return grpc_empty_slice();
+}
+
+grpc_mdelem grpc_compression_encoding_mdelem(
+    grpc_compression_algorithm algorithm) {
+  switch (algorithm) {
+    case GRPC_COMPRESS_NONE:
+      return GRPC_MDELEM_GRPC_ENCODING_IDENTITY;
+    case GRPC_COMPRESS_DEFLATE:
+      return GRPC_MDELEM_GRPC_ENCODING_DEFLATE;
+    case GRPC_COMPRESS_GZIP:
+      return GRPC_MDELEM_GRPC_ENCODING_GZIP;
+    default:
+      break;
+  }
+  return GRPC_MDNULL;
+}
+
+grpc_mdelem grpc_stream_compression_encoding_mdelem(
+    grpc_stream_compression_algorithm algorithm) {
+  switch (algorithm) {
+    case GRPC_STREAM_COMPRESS_NONE:
+      return GRPC_MDELEM_CONTENT_ENCODING_IDENTITY;
+    case GRPC_STREAM_COMPRESS_GZIP:
+      return GRPC_MDELEM_CONTENT_ENCODING_GZIP;
+    default:
+      break;
+  }
+  return GRPC_MDNULL;
+}
+
+void grpc_compression_options_init(grpc_compression_options *opts) {
+  memset(opts, 0, sizeof(*opts));
+  /* all enabled by default */
+  opts->enabled_algorithms_bitset = (1u << GRPC_COMPRESS_ALGORITHMS_COUNT) - 1;
+  opts->enabled_stream_compression_algorithms_bitset =
+      (1u << GRPC_STREAM_COMPRESS_ALGORITHMS_COUNT) - 1;
+}
+
+void grpc_compression_options_enable_algorithm(
+    grpc_compression_options *opts, grpc_compression_algorithm algorithm) {
+  GPR_BITSET(&opts->enabled_algorithms_bitset, algorithm);
+}
+
+void grpc_compression_options_disable_algorithm(
+    grpc_compression_options *opts, grpc_compression_algorithm algorithm) {
+  GPR_BITCLEAR(&opts->enabled_algorithms_bitset, algorithm);
+}
+
+int grpc_compression_options_is_algorithm_enabled(
+    const grpc_compression_options *opts,
+    grpc_compression_algorithm algorithm) {
+  return GPR_BITGET(opts->enabled_algorithms_bitset, algorithm);
+}
+
+int grpc_compression_options_is_stream_compression_algorithm_enabled(
+    const grpc_compression_options *opts,
+    grpc_stream_compression_algorithm algorithm) {
+  return GPR_BITGET(opts->enabled_stream_compression_algorithms_bitset,
+                    algorithm);
+}
+
+/* TODO(dgq): Add the ability to specify parameters to the individual
+ * compression algorithms */
+grpc_compression_algorithm grpc_compression_algorithm_for_level(
+    grpc_compression_level level, uint32_t accepted_encodings) {
+  GRPC_API_TRACE("grpc_compression_algorithm_for_level(level=%d)", 1,
+                 ((int)level));
+  if (level > GRPC_COMPRESS_LEVEL_HIGH) {
+    gpr_log(GPR_ERROR, "Unknown compression level %d.", (int)level);
+    abort();
+  }
+
+  const size_t num_supported =
+      GPR_BITCOUNT(accepted_encodings) - 1; /* discard NONE */
+  if (level == GRPC_COMPRESS_LEVEL_NONE || num_supported == 0) {
+    return GRPC_COMPRESS_NONE;
+  }
+
+  GPR_ASSERT(level > 0);
+
+  /* Establish a "ranking" or compression algorithms in increasing order of
+   * compression.
+   * This is simplistic and we will probably want to introduce other dimensions
+   * in the future (cpu/memory cost, etc). */
+  const grpc_compression_algorithm algos_ranking[] = {GRPC_COMPRESS_GZIP,
+                                                      GRPC_COMPRESS_DEFLATE};
+
+  /* intersect algos_ranking with the supported ones keeping the ranked order */
+  grpc_compression_algorithm
+      sorted_supported_algos[GRPC_COMPRESS_ALGORITHMS_COUNT];
+  size_t algos_supported_idx = 0;
+  for (size_t i = 0; i < GPR_ARRAY_SIZE(algos_ranking); i++) {
+    const grpc_compression_algorithm alg = algos_ranking[i];
+    for (size_t j = 0; j < num_supported; j++) {
+      if (GPR_BITGET(accepted_encodings, alg) == 1) {
+        /* if \a alg in supported */
+        sorted_supported_algos[algos_supported_idx++] = alg;
+        break;
+      }
+    }
+    if (algos_supported_idx == num_supported) break;
+  }
+
+  switch (level) {
+    case GRPC_COMPRESS_LEVEL_NONE:
+      abort(); /* should have been handled already */
+    case GRPC_COMPRESS_LEVEL_LOW:
+      return sorted_supported_algos[0];
+    case GRPC_COMPRESS_LEVEL_MED:
+      return sorted_supported_algos[num_supported / 2];
+    case GRPC_COMPRESS_LEVEL_HIGH:
+      return sorted_supported_algos[num_supported - 1];
+    default:
+      abort();
+  };
+}
+
+GRPCAPI grpc_stream_compression_algorithm
+grpc_stream_compression_algorithm_for_level(
+    grpc_stream_compression_level level, uint32_t accepted_stream_encodings) {
+  GRPC_API_TRACE("grpc_stream_compression_algorithm_for_level(level=%d)", 1,
+                 ((int)level));
+  if (level > GRPC_STREAM_COMPRESS_LEVEL_HIGH) {
+    gpr_log(GPR_ERROR, "Unknown compression level %d.", (int)level);
+    abort();
+  }
+
+  switch (level) {
+    case GRPC_STREAM_COMPRESS_LEVEL_NONE:
+      return GRPC_STREAM_COMPRESS_NONE;
+    case GRPC_STREAM_COMPRESS_LEVEL_LOW:
+    case GRPC_STREAM_COMPRESS_LEVEL_MED:
+    case GRPC_STREAM_COMPRESS_LEVEL_HIGH:
+      if (GPR_BITGET(accepted_stream_encodings, GRPC_STREAM_COMPRESS_GZIP) ==
+          1) {
+        return GRPC_STREAM_COMPRESS_GZIP;
+      } else {
+        return GRPC_STREAM_COMPRESS_NONE;
+      }
+    default:
+      abort();
+  }
+}