include/grpc/impl/codegen/grpc_types.h

/*
 *
 * Copyright 2015-2016, Google Inc.
 * All rights reserved.
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 * modification, are permitted provided that the following conditions are
 * met:
 *
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 * 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
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 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
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#ifndef GRPC_IMPL_CODEGEN_GRPC_TYPES_H
#define GRPC_IMPL_CODEGEN_GRPC_TYPES_H

#include <grpc/impl/codegen/byte_buffer.h>
#include <grpc/impl/codegen/status.h>

#include <stddef.h>

#ifdef __cplusplus
extern "C" {
#endif

/** Completion Queues enable notification of the completion of asynchronous
    actions. */
typedef struct grpc_completion_queue grpc_completion_queue;

/** An alarm associated with a completion queue. */
typedef struct grpc_alarm grpc_alarm;

/** The Channel interface allows creation of Call objects. */
typedef struct grpc_channel grpc_channel;

/** A server listens to some port and responds to request calls */
typedef struct grpc_server grpc_server;

/** A Call represents an RPC. When created, it is in a configuration state
    allowing properties to be set until it is invoked. After invoke, the Call
    can have messages written to it and read from it. */
typedef struct grpc_call grpc_call;

/** Type specifier for grpc_arg */
typedef enum {
  GRPC_ARG_STRING,
  GRPC_ARG_INTEGER,
  GRPC_ARG_POINTER
} grpc_arg_type;

/** A single argument... each argument has a key and a value

    A note on naming keys:
      Keys are namespaced into groups, usually grouped by library, and are
      keys for module XYZ are named XYZ.key1, XYZ.key2, etc. Module names must
      be restricted to the regex [A-Za-z][_A-Za-z0-9]{,15}.
      Key names must be restricted to the regex [A-Za-z][_A-Za-z0-9]{,47}.

    GRPC core library keys are prefixed by grpc.

    Library authors are strongly encouraged to \#define symbolic constants for
    their keys so that it's possible to change them in the future. */
typedef struct {
  grpc_arg_type type;
  char *key;
  union {
    char *string;
    int integer;
    struct {
      void *p;
      void *(*copy)(void *p);
      void (*destroy)(void *p);
    } pointer;
  } value;
} grpc_arg;

/** An array of arguments that can be passed around.

    Used to set optional channel-level configuration.
    These configuration options are modelled as key-value pairs as defined
    by grpc_arg; keys are strings to allow easy backwards-compatible extension
    by arbitrary parties.
    All evaluation is performed at channel creation time (i.e. the values in
    this structure need only live through the creation invocation). */
typedef struct {
  size_t num_args;
  grpc_arg *args;
} grpc_channel_args;

/* Channel argument keys: */
/** Enable census for tracing and stats collection */
#define GRPC_ARG_ENABLE_CENSUS "grpc.census"
/** Maximum number of concurrent incoming streams to allow on a http2
    connection */
#define GRPC_ARG_MAX_CONCURRENT_STREAMS "grpc.max_concurrent_streams"
/** Maximum message length that the channel can receive */
#define GRPC_ARG_MAX_MESSAGE_LENGTH "grpc.max_message_length"
/** Initial sequence number for http2 transports */
#define GRPC_ARG_HTTP2_INITIAL_SEQUENCE_NUMBER \
  "grpc.http2.initial_sequence_number"
/** Amount to read ahead on individual streams. Defaults to 64kb, larger
    values can help throughput on high-latency connections.
    NOTE: at some point we'd like to auto-tune this, and this parameter
    will become a no-op. */
#define GRPC_ARG_HTTP2_STREAM_LOOKAHEAD_BYTES "grpc.http2.lookahead_bytes"
/** How much memory to use for hpack decoding */
#define GRPC_ARG_HTTP2_HPACK_TABLE_SIZE_DECODER \
  "grpc.http2.hpack_table_size.decoder"
/** How much memory to use for hpack encoding */
#define GRPC_ARG_HTTP2_HPACK_TABLE_SIZE_ENCODER \
  "grpc.http2.hpack_table_size.encoder"
/** Default authority to pass if none specified on call construction */
#define GRPC_ARG_DEFAULT_AUTHORITY "grpc.default_authority"
/** Primary user agent: goes at the start of the user-agent metadata
    sent on each request */
#define GRPC_ARG_PRIMARY_USER_AGENT_STRING "grpc.primary_user_agent"
/** Secondary user agent: goes at the end of the user-agent metadata
    sent on each request */
#define GRPC_ARG_SECONDARY_USER_AGENT_STRING "grpc.secondary_user_agent"
/* The caller of the secure_channel_create functions may override the target
   name used for SSL host name checking using this channel argument which is of
   type GRPC_ARG_STRING. This *should* be used for testing only.
   If this argument is not specified, the name used for SSL host name checking
   will be the target parameter (assuming that the secure channel is an SSL
   channel). If this parameter is specified and the underlying is not an SSL
   channel, it will just be ignored. */
#define GRPC_SSL_TARGET_NAME_OVERRIDE_ARG "grpc.ssl_target_name_override"

/** Result of a grpc call. If the caller satisfies the prerequisites of a
    particular operation, the grpc_call_error returned will be GRPC_CALL_OK.
    Receiving any other value listed here is an indication of a bug in the
    caller. */
typedef enum grpc_call_error {
  /** everything went ok */
  GRPC_CALL_OK = 0,
  /** something failed, we don't know what */
  GRPC_CALL_ERROR,
  /** this method is not available on the server */
  GRPC_CALL_ERROR_NOT_ON_SERVER,
  /** this method is not available on the client */
  GRPC_CALL_ERROR_NOT_ON_CLIENT,
  /** this method must be called before server_accept */
  GRPC_CALL_ERROR_ALREADY_ACCEPTED,
  /** this method must be called before invoke */
  GRPC_CALL_ERROR_ALREADY_INVOKED,
  /** this method must be called after invoke */
  GRPC_CALL_ERROR_NOT_INVOKED,
  /** this call is already finished
      (writes_done or write_status has already been called) */
  GRPC_CALL_ERROR_ALREADY_FINISHED,
  /** there is already an outstanding read/write operation on the call */
  GRPC_CALL_ERROR_TOO_MANY_OPERATIONS,
  /** the flags value was illegal for this call */
  GRPC_CALL_ERROR_INVALID_FLAGS,
  /** invalid metadata was passed to this call */
  GRPC_CALL_ERROR_INVALID_METADATA,
  /** invalid message was passed to this call */
  GRPC_CALL_ERROR_INVALID_MESSAGE,
  /** completion queue for notification has not been registered with the
      server */
  GRPC_CALL_ERROR_NOT_SERVER_COMPLETION_QUEUE,
  /** this batch of operations leads to more operations than allowed */
  GRPC_CALL_ERROR_BATCH_TOO_BIG
} grpc_call_error;

/* Write Flags: */
/** Hint that the write may be buffered and need not go out on the wire
    immediately. GRPC is free to buffer the message until the next non-buffered
    write, or until writes_done, but it need not buffer completely or at all. */
#define GRPC_WRITE_BUFFER_HINT (0x00000001u)
/** Force compression to be disabled for a particular write
    (start_write/add_metadata). Illegal on invoke/accept. */
#define GRPC_WRITE_NO_COMPRESS (0x00000002u)
/** Mask of all valid flags. */
#define GRPC_WRITE_USED_MASK (GRPC_WRITE_BUFFER_HINT | GRPC_WRITE_NO_COMPRESS)

/** A single metadata element */
typedef struct grpc_metadata {
  const char *key;
  const char *value;
  size_t value_length;
  uint32_t flags;

  /** The following fields are reserved for grpc internal use.
      There is no need to initialize them, and they will be set to garbage
      during calls to grpc. */
  struct {
    void *obfuscated[4];
  } internal_data;
} grpc_metadata;

/** The type of completion (for grpc_event) */
typedef enum grpc_completion_type {
  /** Shutting down */
  GRPC_QUEUE_SHUTDOWN,
  /** No event before timeout */
  GRPC_QUEUE_TIMEOUT,
  /** Operation completion */
  GRPC_OP_COMPLETE
} grpc_completion_type;

/** The result of an operation.

    Returned by a completion queue when the operation started with tag. */
typedef struct grpc_event {
  /** The type of the completion. */
  grpc_completion_type type;
  /** non-zero if the operation was successful, 0 upon failure.
      Only GRPC_OP_COMPLETE can succeed or fail. */
  int success;
  /** The tag passed to grpc_call_start_batch etc to start this operation.
      Only GRPC_OP_COMPLETE has a tag. */
  void *tag;
} grpc_event;

typedef struct {
  size_t count;
  size_t capacity;
  grpc_metadata *metadata;
} grpc_metadata_array;

typedef struct {
  char *method;
  size_t method_capacity;
  char *host;
  size_t host_capacity;
  gpr_timespec deadline;
  void *reserved;
} grpc_call_details;

typedef enum {
  /** Send initial metadata: one and only one instance MUST be sent for each
      call, unless the call was cancelled - in which case this can be skipped.
      This op completes after all bytes of metadata have been accepted by
      outgoing flow control. */
  GRPC_OP_SEND_INITIAL_METADATA = 0,
  /** Send a message: 0 or more of these operations can occur for each call.
      This op completes after all bytes for the message have been accepted by
      outgoing flow control. */
  GRPC_OP_SEND_MESSAGE,
  /** Send a close from the client: one and only one instance MUST be sent from
      the client, unless the call was cancelled - in which case this can be
      skipped.
      This op completes after all bytes for the call (including the close)
      have passed outgoing flow control. */
  GRPC_OP_SEND_CLOSE_FROM_CLIENT,
  /** Send status from the server: one and only one instance MUST be sent from
      the server unless the call was cancelled - in which case this can be
      skipped.
      This op completes after all bytes for the call (including the status)
      have passed outgoing flow control. */
  GRPC_OP_SEND_STATUS_FROM_SERVER,
  /** Receive initial metadata: one and only one MUST be made on the client,
      must not be made on the server.
      This op completes after all initial metadata has been read from the
      peer. */
  GRPC_OP_RECV_INITIAL_METADATA,
  /** Receive a message: 0 or more of these operations can occur for each call.
      This op completes after all bytes of the received message have been
      read, or after a half-close has been received on this call. */
  GRPC_OP_RECV_MESSAGE,
  /** Receive status on the client: one and only one must be made on the client.
      This operation always succeeds, meaning ops paired with this operation
      will also appear to succeed, even though they may not have. In that case
      the status will indicate some failure.
      This op completes after all activity on the call has completed. */
  GRPC_OP_RECV_STATUS_ON_CLIENT,
  /** Receive close on the server: one and only one must be made on the
      server.
      This op completes after the close has been received by the server. */
  GRPC_OP_RECV_CLOSE_ON_SERVER
} grpc_op_type;

/** Operation data: one field for each op type (except SEND_CLOSE_FROM_CLIENT
   which has no arguments) */
typedef struct grpc_op {
  /** Operation type, as defined by grpc_op_type */
  grpc_op_type op;
  /** Write flags bitset for grpc_begin_messages */
  uint32_t flags;
  /** Reserved for future usage */
  void *reserved;
  union {
    /** Reserved for future usage */
    struct {
      void *reserved[8];
    } reserved;
    struct {
      size_t count;
      grpc_metadata *metadata;
    } send_initial_metadata;
    grpc_byte_buffer *send_message;
    struct {
      size_t trailing_metadata_count;
      grpc_metadata *trailing_metadata;
      grpc_status_code status;
      const char *status_details;
    } send_status_from_server;
    /** ownership of the array is with the caller, but ownership of the elements
        stays with the call object (ie key, value members are owned by the call
        object, recv_initial_metadata->array is owned by the caller).
        After the operation completes, call grpc_metadata_array_destroy on this
        value, or reuse it in a future op. */
    grpc_metadata_array *recv_initial_metadata;
    /** ownership of the byte buffer is moved to the caller; the caller must
        call grpc_byte_buffer_destroy on this value, or reuse it in a future op.
       */
    grpc_byte_buffer **recv_message;
    struct {
      /** ownership of the array is with the caller, but ownership of the
          elements stays with the call object (ie key, value members are owned
          by the call object, trailing_metadata->array is owned by the caller).
          After the operation completes, call grpc_metadata_array_destroy on
         this
          value, or reuse it in a future op. */
      grpc_metadata_array *trailing_metadata;
      grpc_status_code *status;
      /** status_details is a buffer owned by the application before the op
          completes and after the op has completed. During the operation
          status_details may be reallocated to a size larger than
          *status_details_capacity, in which case *status_details_capacity will
          be updated with the new array capacity.

          Pre-allocating space:
          size_t my_capacity = 8;
          char *my_details = gpr_malloc(my_capacity);
          x.status_details = &my_details;
          x.status_details_capacity = &my_capacity;

          Not pre-allocating space:
          size_t my_capacity = 0;
          char *my_details = NULL;
          x.status_details = &my_details;
          x.status_details_capacity = &my_capacity;

          After the call:
          gpr_free(my_details); */
      char **status_details;
      size_t *status_details_capacity;
    } recv_status_on_client;
    struct {
      /** out argument, set to 1 if the call failed in any way (seen as a
          cancellation on the server), or 0 if the call succeeded */
      int *cancelled;
    } recv_close_on_server;
  } data;
} grpc_op;

#ifdef __cplusplus
}
#endif

#endif /* GRPC_IMPL_CODEGEN_GRPC_TYPES_H */