1 files changed, 360 insertions, 0 deletions

diff --git a/src/core/lib/slice/slice_buffer.cc b/src/core/lib/slice/slice_buffer.cc
new file mode 100644
index 0000000000..63ffc0b00d
--- /dev/null
+++ b/src/core/lib/slice/slice_buffer.cc
@@ -0,0 +1,360 @@
+/*
+ *
+ * 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 <grpc/slice_buffer.h>
+#include <grpc/support/port_platform.h>
+
+#include <string.h>
+
+#include <grpc/support/alloc.h>
+#include <grpc/support/log.h>
+#include <grpc/support/useful.h>
+
+#include "src/core/lib/slice/slice_internal.h"
+
+/* grow a buffer; requires GRPC_SLICE_BUFFER_INLINE_ELEMENTS > 1 */
+#define GROW(x) (3 * (x) / 2)
+
+static void maybe_embiggen(grpc_slice_buffer *sb) {
+  /* How far away from sb->base_slices is sb->slices pointer */
+  size_t slice_offset = (size_t)(sb->slices - sb->base_slices);
+  size_t slice_count = sb->count + slice_offset;
+
+  if (slice_count == sb->capacity) {
+    if (sb->base_slices != sb->slices) {
+      /* Make room by moving elements if there's still space unused */
+      memmove(sb->base_slices, sb->slices, sb->count * sizeof(grpc_slice));
+      sb->slices = sb->base_slices;
+    } else {
+      /* Allocate more memory if no more space is available */
+      sb->capacity = GROW(sb->capacity);
+      GPR_ASSERT(sb->capacity > slice_count);
+      if (sb->base_slices == sb->inlined) {
+        sb->base_slices =
+            (grpc_slice *)gpr_malloc(sb->capacity * sizeof(grpc_slice));
+        memcpy(sb->base_slices, sb->inlined, slice_count * sizeof(grpc_slice));
+      } else {
+        sb->base_slices = (grpc_slice *)gpr_realloc(
+            sb->base_slices, sb->capacity * sizeof(grpc_slice));
+      }
+
+      sb->slices = sb->base_slices + slice_offset;
+    }
+  }
+}
+
+void grpc_slice_buffer_init(grpc_slice_buffer *sb) {
+  sb->count = 0;
+  sb->length = 0;
+  sb->capacity = GRPC_SLICE_BUFFER_INLINE_ELEMENTS;
+  sb->base_slices = sb->slices = sb->inlined;
+}
+
+void grpc_slice_buffer_destroy_internal(grpc_exec_ctx *exec_ctx,
+                                        grpc_slice_buffer *sb) {
+  grpc_slice_buffer_reset_and_unref_internal(exec_ctx, sb);
+  if (sb->base_slices != sb->inlined) {
+    gpr_free(sb->base_slices);
+  }
+}
+
+void grpc_slice_buffer_destroy(grpc_slice_buffer *sb) {
+  grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
+  grpc_slice_buffer_destroy_internal(&exec_ctx, sb);
+  grpc_exec_ctx_finish(&exec_ctx);
+}
+
+uint8_t *grpc_slice_buffer_tiny_add(grpc_slice_buffer *sb, size_t n) {
+  grpc_slice *back;
+  uint8_t *out;
+
+  sb->length += n;
+
+  if (sb->count == 0) goto add_new;
+  back = &sb->slices[sb->count - 1];
+  if (back->refcount) goto add_new;
+  if ((back->data.inlined.length + n) > sizeof(back->data.inlined.bytes))
+    goto add_new;
+  out = back->data.inlined.bytes + back->data.inlined.length;
+  back->data.inlined.length = (uint8_t)(back->data.inlined.length + n);
+  return out;
+
+add_new:
+  maybe_embiggen(sb);
+  back = &sb->slices[sb->count];
+  sb->count++;
+  back->refcount = NULL;
+  back->data.inlined.length = (uint8_t)n;
+  return back->data.inlined.bytes;
+}
+
+size_t grpc_slice_buffer_add_indexed(grpc_slice_buffer *sb, grpc_slice s) {
+  size_t out = sb->count;
+  maybe_embiggen(sb);
+  sb->slices[out] = s;
+  sb->length += GRPC_SLICE_LENGTH(s);
+  sb->count = out + 1;
+  return out;
+}
+
+void grpc_slice_buffer_add(grpc_slice_buffer *sb, grpc_slice s) {
+  size_t n = sb->count;
+  /* if both the last slice in the slice buffer and the slice being added
+     are inlined (that is, that they carry their data inside the slice data
+     structure), and the back slice is not full, then concatenate directly
+     into the back slice, preventing many small slices being passed into
+     writes */
+  if (!s.refcount && n) {
+    grpc_slice *back = &sb->slices[n - 1];
+    if (!back->refcount &&
+        back->data.inlined.length < GRPC_SLICE_INLINED_SIZE) {
+      if (s.data.inlined.length + back->data.inlined.length <=
+          GRPC_SLICE_INLINED_SIZE) {
+        memcpy(back->data.inlined.bytes + back->data.inlined.length,
+               s.data.inlined.bytes, s.data.inlined.length);
+        back->data.inlined.length =
+            (uint8_t)(back->data.inlined.length + s.data.inlined.length);
+      } else {
+        size_t cp1 = GRPC_SLICE_INLINED_SIZE - back->data.inlined.length;
+        memcpy(back->data.inlined.bytes + back->data.inlined.length,
+               s.data.inlined.bytes, cp1);
+        back->data.inlined.length = GRPC_SLICE_INLINED_SIZE;
+        maybe_embiggen(sb);
+        back = &sb->slices[n];
+        sb->count = n + 1;
+        back->refcount = NULL;
+        back->data.inlined.length = (uint8_t)(s.data.inlined.length - cp1);
+        memcpy(back->data.inlined.bytes, s.data.inlined.bytes + cp1,
+               s.data.inlined.length - cp1);
+      }
+      sb->length += s.data.inlined.length;
+      return; /* early out */
+    }
+  }
+  grpc_slice_buffer_add_indexed(sb, s);
+}
+
+void grpc_slice_buffer_addn(grpc_slice_buffer *sb, grpc_slice *s, size_t n) {
+  size_t i;
+  for (i = 0; i < n; i++) {
+    grpc_slice_buffer_add(sb, s[i]);
+  }
+}
+
+void grpc_slice_buffer_pop(grpc_slice_buffer *sb) {
+  if (sb->count != 0) {
+    size_t count = --sb->count;
+    sb->length -= GRPC_SLICE_LENGTH(sb->slices[count]);
+  }
+}
+
+void grpc_slice_buffer_reset_and_unref_internal(grpc_exec_ctx *exec_ctx,
+                                                grpc_slice_buffer *sb) {
+  size_t i;
+  for (i = 0; i < sb->count; i++) {
+    grpc_slice_unref_internal(exec_ctx, sb->slices[i]);
+  }
+
+  sb->count = 0;
+  sb->length = 0;
+}
+
+void grpc_slice_buffer_reset_and_unref(grpc_slice_buffer *sb) {
+  grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
+  grpc_slice_buffer_reset_and_unref_internal(&exec_ctx, sb);
+  grpc_exec_ctx_finish(&exec_ctx);
+}
+
+void grpc_slice_buffer_swap(grpc_slice_buffer *a, grpc_slice_buffer *b) {
+  size_t a_offset = (size_t)(a->slices - a->base_slices);
+  size_t b_offset = (size_t)(b->slices - b->base_slices);
+
+  size_t a_count = a->count + a_offset;
+  size_t b_count = b->count + b_offset;
+
+  if (a->base_slices == a->inlined) {
+    if (b->base_slices == b->inlined) {
+      /* swap contents of inlined buffer */
+      grpc_slice temp[GRPC_SLICE_BUFFER_INLINE_ELEMENTS];
+      memcpy(temp, a->base_slices, a_count * sizeof(grpc_slice));
+      memcpy(a->base_slices, b->base_slices, b_count * sizeof(grpc_slice));
+      memcpy(b->base_slices, temp, a_count * sizeof(grpc_slice));
+    } else {
+      /* a is inlined, b is not - copy a inlined into b, fix pointers */
+      a->base_slices = b->base_slices;
+      b->base_slices = b->inlined;
+      memcpy(b->base_slices, a->inlined, a_count * sizeof(grpc_slice));
+    }
+  } else if (b->base_slices == b->inlined) {
+    /* b is inlined, a is not - copy b inlined int a, fix pointers */
+    b->base_slices = a->base_slices;
+    a->base_slices = a->inlined;
+    memcpy(a->base_slices, b->inlined, b_count * sizeof(grpc_slice));
+  } else {
+    /* no inlining: easy swap */
+    GPR_SWAP(grpc_slice *, a->base_slices, b->base_slices);
+  }
+
+  /* Update the slices pointers (cannot do a GPR_SWAP on slices fields here).
+   * Also note that since the base_slices pointers are already swapped we need
+   * use 'b_offset' for 'a->base_slices' and vice versa */
+  a->slices = a->base_slices + b_offset;
+  b->slices = b->base_slices + a_offset;
+
+  /* base_slices and slices fields are correctly set. Swap all other fields */
+  GPR_SWAP(size_t, a->count, b->count);
+  GPR_SWAP(size_t, a->capacity, b->capacity);
+  GPR_SWAP(size_t, a->length, b->length);
+}
+
+void grpc_slice_buffer_move_into(grpc_slice_buffer *src,
+                                 grpc_slice_buffer *dst) {
+  /* anything to move? */
+  if (src->count == 0) {
+    return;
+  }
+  /* anything in dst? */
+  if (dst->count == 0) {
+    grpc_slice_buffer_swap(src, dst);
+    return;
+  }
+  /* both buffers have data - copy, and reset src */
+  grpc_slice_buffer_addn(dst, src->slices, src->count);
+  src->count = 0;
+  src->length = 0;
+}
+
+static void slice_buffer_move_first_maybe_ref(grpc_slice_buffer *src, size_t n,
+                                              grpc_slice_buffer *dst,
+                                              bool incref) {
+  GPR_ASSERT(src->length >= n);
+  if (src->length == n) {
+    grpc_slice_buffer_move_into(src, dst);
+    return;
+  }
+
+  size_t output_len = dst->length + n;
+  size_t new_input_len = src->length - n;
+
+  while (src->count > 0) {
+    grpc_slice slice = grpc_slice_buffer_take_first(src);
+    size_t slice_len = GRPC_SLICE_LENGTH(slice);
+    if (n > slice_len) {
+      grpc_slice_buffer_add(dst, slice);
+      n -= slice_len;
+    } else if (n == slice_len) {
+      grpc_slice_buffer_add(dst, slice);
+      break;
+    } else if (incref) { /* n < slice_len */
+      grpc_slice_buffer_undo_take_first(
+          src, grpc_slice_split_tail_maybe_ref(&slice, n, GRPC_SLICE_REF_BOTH));
+      GPR_ASSERT(GRPC_SLICE_LENGTH(slice) == n);
+      grpc_slice_buffer_add(dst, slice);
+      break;
+    } else { /* n < slice_len */
+      grpc_slice_buffer_undo_take_first(
+          src, grpc_slice_split_tail_maybe_ref(&slice, n, GRPC_SLICE_REF_TAIL));
+      GPR_ASSERT(GRPC_SLICE_LENGTH(slice) == n);
+      grpc_slice_buffer_add_indexed(dst, slice);
+      break;
+    }
+  }
+  GPR_ASSERT(dst->length == output_len);
+  GPR_ASSERT(src->length == new_input_len);
+  GPR_ASSERT(src->count > 0);
+}
+
+void grpc_slice_buffer_move_first(grpc_slice_buffer *src, size_t n,
+                                  grpc_slice_buffer *dst) {
+  slice_buffer_move_first_maybe_ref(src, n, dst, true);
+}
+
+void grpc_slice_buffer_move_first_no_ref(grpc_slice_buffer *src, size_t n,
+                                         grpc_slice_buffer *dst) {
+  slice_buffer_move_first_maybe_ref(src, n, dst, false);
+}
+
+void grpc_slice_buffer_move_first_into_buffer(grpc_exec_ctx *exec_ctx,
+                                              grpc_slice_buffer *src, size_t n,
+                                              void *dst) {
+  char *dstp = (char *)dst;
+  GPR_ASSERT(src->length >= n);
+
+  while (n > 0) {
+    grpc_slice slice = grpc_slice_buffer_take_first(src);
+    size_t slice_len = GRPC_SLICE_LENGTH(slice);
+    if (slice_len > n) {
+      memcpy(dstp, GRPC_SLICE_START_PTR(slice), n);
+      grpc_slice_buffer_undo_take_first(
+          src, grpc_slice_sub_no_ref(slice, n, slice_len));
+      n = 0;
+    } else if (slice_len == n) {
+      memcpy(dstp, GRPC_SLICE_START_PTR(slice), n);
+      grpc_slice_unref_internal(exec_ctx, slice);
+      n = 0;
+    } else {
+      memcpy(dstp, GRPC_SLICE_START_PTR(slice), slice_len);
+      dstp += slice_len;
+      n -= slice_len;
+      grpc_slice_unref_internal(exec_ctx, slice);
+    }
+  }
+}
+
+void grpc_slice_buffer_trim_end(grpc_slice_buffer *sb, size_t n,
+                                grpc_slice_buffer *garbage) {
+  GPR_ASSERT(n <= sb->length);
+  sb->length -= n;
+  for (;;) {
+    size_t idx = sb->count - 1;
+    grpc_slice slice = sb->slices[idx];
+    size_t slice_len = GRPC_SLICE_LENGTH(slice);
+    if (slice_len > n) {
+      sb->slices[idx] = grpc_slice_split_head(&slice, slice_len - n);
+      grpc_slice_buffer_add_indexed(garbage, slice);
+      return;
+    } else if (slice_len == n) {
+      grpc_slice_buffer_add_indexed(garbage, slice);
+      sb->count = idx;
+      return;
+    } else {
+      grpc_slice_buffer_add_indexed(garbage, slice);
+      n -= slice_len;
+      sb->count = idx;
+    }
+  }
+}
+
+grpc_slice grpc_slice_buffer_take_first(grpc_slice_buffer *sb) {
+  grpc_slice slice;
+  GPR_ASSERT(sb->count > 0);
+  slice = sb->slices[0];
+  sb->slices++;
+  sb->count--;
+  sb->length -= GRPC_SLICE_LENGTH(slice);
+
+  return slice;
+}
+
+void grpc_slice_buffer_undo_take_first(grpc_slice_buffer *sb,
+                                       grpc_slice slice) {
+  sb->slices--;
+  sb->slices[0] = slice;
+  sb->count++;
+  sb->length += GRPC_SLICE_LENGTH(slice);
+}