mojo/public/c/system/types.h

// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

// This file contains types and constants/macros common to different Mojo system
// APIs.
//
// Note: This header should be compilable as C.

#ifndef MOJO_PUBLIC_C_SYSTEM_TYPES_H_
#define MOJO_PUBLIC_C_SYSTEM_TYPES_H_

#include <stdint.h>

#include "mojo/public/c/system/macros.h"

// |MojoTimeTicks|: A time delta, in microseconds, the meaning of which is
// source-dependent.

typedef int64_t MojoTimeTicks;

// |MojoHandle|: Handles to Mojo objects.
//   |MOJO_HANDLE_INVALID| - A value that is never a valid handle.

typedef uint32_t MojoHandle;

#ifdef __cplusplus
const MojoHandle MOJO_HANDLE_INVALID = 0;
#else
#define MOJO_HANDLE_INVALID ((MojoHandle)0)
#endif

// |MojoResult|: Result codes for Mojo operations. The only success code is zero
// (|MOJO_RESULT_OK|); all non-zero values should be considered as error/failure
// codes (even if the value is not recognized).
//   |MOJO_RESULT_OK| - Not an error; returned on success.
//   |MOJO_RESULT_CANCELLED| - Operation was cancelled, typically by the caller.
//   |MOJO_RESULT_UNKNOWN| - Unknown error (e.g., if not enough information is
//       available for a more specific error).
//   |MOJO_RESULT_INVALID_ARGUMENT| - Caller specified an invalid argument. This
//       differs from |MOJO_RESULT_FAILED_PRECONDITION| in that the former
//       indicates arguments that are invalid regardless of the state of the
//       system.
//   |MOJO_RESULT_DEADLINE_EXCEEDED| - Deadline expired before the operation
//       could complete.
//   |MOJO_RESULT_NOT_FOUND| - Some requested entity was not found (i.e., does
//       not exist).
//   |MOJO_RESULT_ALREADY_EXISTS| - Some entity or condition that we attempted
//       to create already exists.
//   |MOJO_RESULT_PERMISSION_DENIED| - The caller does not have permission to
//       for the operation (use |MOJO_RESULT_RESOURCE_EXHAUSTED| for rejections
//       caused by exhausting some resource instead).
//   |MOJO_RESULT_RESOURCE_EXHAUSTED| - Some resource required for the call
//       (possibly some quota) has been exhausted.
//   |MOJO_RESULT_FAILED_PRECONDITION| - The system is not in a state required
//       for the operation (use this if the caller must do something to rectify
//       the state before retrying).
//   |MOJO_RESULT_ABORTED| - The operation was aborted by the system, possibly
//       due to a concurrency issue (use this if the caller may retry at a
//       higher level).
//   |MOJO_RESULT_OUT_OF_RANGE| - The operation was attempted past the valid
//       range. Unlike |MOJO_RESULT_INVALID_ARGUMENT|, this indicates that the
//       operation may be/become valid depending on the system state. (This
//       error is similar to |MOJO_RESULT_FAILED_PRECONDITION|, but is more
//       specific.)
//   |MOJO_RESULT_UNIMPLEMENTED| - The operation is not implemented, supported,
//       or enabled.
//   |MOJO_RESULT_INTERNAL| - Internal error: this should never happen and
//       indicates that some invariant expected by the system has been broken.
//   |MOJO_RESULT_UNAVAILABLE| - The operation is (temporarily) currently
//       unavailable. The caller may simply retry the operation (possibly with a
//       backoff).
//   |MOJO_RESULT_DATA_LOSS| - Unrecoverable data loss or corruption.
//   |MOJO_RESULT_BUSY| - One of the resources involved is currently being used
//       (possibly on another thread) in a way that prevents the current
//       operation from proceeding, e.g., if the other operation may result in
//       the resource being invalidated.
//   |MOJO_RESULT_SHOULD_WAIT| - The request cannot currently be completed
//       (e.g., if the data requested is not yet available). The caller should
//       wait for it to be feasible using a watcher.
//
// The codes from |MOJO_RESULT_OK| to |MOJO_RESULT_DATA_LOSS| come from
// Google3's canonical error codes.

typedef uint32_t MojoResult;

#ifdef __cplusplus
const MojoResult MOJO_RESULT_OK = 0;
const MojoResult MOJO_RESULT_CANCELLED = 1;
const MojoResult MOJO_RESULT_UNKNOWN = 2;
const MojoResult MOJO_RESULT_INVALID_ARGUMENT = 3;
const MojoResult MOJO_RESULT_DEADLINE_EXCEEDED = 4;
const MojoResult MOJO_RESULT_NOT_FOUND = 5;
const MojoResult MOJO_RESULT_ALREADY_EXISTS = 6;
const MojoResult MOJO_RESULT_PERMISSION_DENIED = 7;
const MojoResult MOJO_RESULT_RESOURCE_EXHAUSTED = 8;
const MojoResult MOJO_RESULT_FAILED_PRECONDITION = 9;
const MojoResult MOJO_RESULT_ABORTED = 10;
const MojoResult MOJO_RESULT_OUT_OF_RANGE = 11;
const MojoResult MOJO_RESULT_UNIMPLEMENTED = 12;
const MojoResult MOJO_RESULT_INTERNAL = 13;
const MojoResult MOJO_RESULT_UNAVAILABLE = 14;
const MojoResult MOJO_RESULT_DATA_LOSS = 15;
const MojoResult MOJO_RESULT_BUSY = 16;
const MojoResult MOJO_RESULT_SHOULD_WAIT = 17;
#else
#define MOJO_RESULT_OK ((MojoResult)0)
#define MOJO_RESULT_CANCELLED ((MojoResult)1)
#define MOJO_RESULT_UNKNOWN ((MojoResult)2)
#define MOJO_RESULT_INVALID_ARGUMENT ((MojoResult)3)
#define MOJO_RESULT_DEADLINE_EXCEEDED ((MojoResult)4)
#define MOJO_RESULT_NOT_FOUND ((MojoResult)5)
#define MOJO_RESULT_ALREADY_EXISTS ((MojoResult)6)
#define MOJO_RESULT_PERMISSION_DENIED ((MojoResult)7)
#define MOJO_RESULT_RESOURCE_EXHAUSTED ((MojoResult)8)
#define MOJO_RESULT_FAILED_PRECONDITION ((MojoResult)9)
#define MOJO_RESULT_ABORTED ((MojoResult)10)
#define MOJO_RESULT_OUT_OF_RANGE ((MojoResult)11)
#define MOJO_RESULT_UNIMPLEMENTED ((MojoResult)12)
#define MOJO_RESULT_INTERNAL ((MojoResult)13)
#define MOJO_RESULT_UNAVAILABLE ((MojoResult)14)
#define MOJO_RESULT_DATA_LOSS ((MojoResult)15)
#define MOJO_RESULT_BUSY ((MojoResult)16)
#define MOJO_RESULT_SHOULD_WAIT ((MojoResult)17)
#endif

// |MojoDeadline|: Used to specify deadlines (timeouts), in microseconds (except
// for |MOJO_DEADLINE_INDEFINITE|).
//   |MOJO_DEADLINE_INDEFINITE| - Used to indicate "forever".

typedef uint64_t MojoDeadline;

#ifdef __cplusplus
const MojoDeadline MOJO_DEADLINE_INDEFINITE = static_cast<MojoDeadline>(-1);
#else
#define MOJO_DEADLINE_INDEFINITE ((MojoDeadline)-1)
#endif

// |MojoHandleSignals|: Used to specify signals that can be watched for on a
// handle (and which can be triggered), e.g., the ability to read or write to
// the handle.
//   |MOJO_HANDLE_SIGNAL_NONE| - No flags. A registered watch will always fail
//       to arm with |MOJO_RESULT_FAILED_PRECONDITION| when watching for this.
//   |MOJO_HANDLE_SIGNAL_READABLE| - Can read (e.g., a message) from the handle.
//   |MOJO_HANDLE_SIGNAL_WRITABLE| - Can write (e.g., a message) to the handle.
//   |MOJO_HANDLE_SIGNAL_PEER_CLOSED| - The peer handle is closed.
//   |MOJO_HANDLE_SIGNAL_NEW_DATA_READABLE| - Can read data from a data pipe
//       consumer handle (implying MOJO_HANDLE_SIGNAL_READABLE is also set),
//       AND there is some nonzero quantity of new data available on the pipe
//       since the last |MojoReadData()| or |MojoBeginReadData()| call on the
//       handle.
//   |MOJO_HANDLE_SIGNAL_PEER_REMOTE| - The peer handle exists in a remote
//       execution context (e.g. in another process.) Note that this signal is
//       maintained with best effort but may at any time be slightly out of sync
//       with the actual location of the peer handle.

typedef uint32_t MojoHandleSignals;

#ifdef __cplusplus
const MojoHandleSignals MOJO_HANDLE_SIGNAL_NONE = 0;
const MojoHandleSignals MOJO_HANDLE_SIGNAL_READABLE = 1 << 0;
const MojoHandleSignals MOJO_HANDLE_SIGNAL_WRITABLE = 1 << 1;
const MojoHandleSignals MOJO_HANDLE_SIGNAL_PEER_CLOSED = 1 << 2;
const MojoHandleSignals MOJO_HANDLE_SIGNAL_NEW_DATA_READABLE = 1 << 3;
const MojoHandleSignals MOJO_HANDLE_SIGNAL_PEER_REMOTE = 1 << 4;
#else
#define MOJO_HANDLE_SIGNAL_NONE ((MojoHandleSignals)0)
#define MOJO_HANDLE_SIGNAL_READABLE ((MojoHandleSignals)1 << 0)
#define MOJO_HANDLE_SIGNAL_WRITABLE ((MojoHandleSignals)1 << 1)
#define MOJO_HANDLE_SIGNAL_PEER_CLOSED ((MojoHandleSignals)1 << 2)
#define MOJO_HANDLE_SIGNAL_NEW_DATA_READABLE ((MojoHandleSignals)1 << 3);
#define MOJO_HANDLE_SIGNAL_PEER_REMOTE ((MojoHandleSignals)1 << 4);
#endif

// |MojoHandleSignalsState|: Returned by watch notification callbacks and
// |MojoQueryHandleSignalsState| functions to indicate the signaling state of
// handles. Members are as follows:
//   - |satisfied signals|: Bitmask of signals that were satisfied at some time
//         before the call returned.
//   - |satisfiable signals|: These are the signals that are possible to
//         satisfy. For example, if the return value was
//         |MOJO_RESULT_FAILED_PRECONDITION|, you can use this field to
//         determine which, if any, of the signals can still be satisfied.
// Note: This struct is not extensible (and only has 32-bit quantities), so it's
// 32-bit-aligned.
MOJO_STATIC_ASSERT(MOJO_ALIGNOF(int32_t) == 4, "int32_t has weird alignment");
struct MOJO_ALIGNAS(4) MojoHandleSignalsState {
  MojoHandleSignals satisfied_signals;
  MojoHandleSignals satisfiable_signals;
};
MOJO_STATIC_ASSERT(sizeof(MojoHandleSignalsState) == 8,
                   "MojoHandleSignalsState has wrong size");

// |MojoWatcherNotificationFlags|: Passed to a callback invoked by a watcher
// when some observed signals are raised or a watched handle is closed. May take
// on any combination of the following values:
//
//   |MOJO_WATCHER_NOTIFICATION_FLAG_FROM_SYSTEM| - The callback is being
//       invoked as a result of a system-level event rather than a direct API
//       call from user code. This may be used as an indication that user code
//       is safe to call without fear of reentry.

typedef uint32_t MojoWatcherNotificationFlags;

#ifdef __cplusplus
const MojoWatcherNotificationFlags MOJO_WATCHER_NOTIFICATION_FLAG_NONE = 0;
const MojoWatcherNotificationFlags MOJO_WATCHER_NOTIFICATION_FLAG_FROM_SYSTEM =
    1 << 0;
#else
#define MOJO_WATCHER_NOTIFICATION_FLAG_NONE ((MojoWatcherNotificationFlags)0)
#define MOJO_WATCHER_NOTIFICATION_FLAG_FROM_SYSTEM \
  ((MojoWatcherNotificationFlags)1 << 0);
#endif

// |MojoWatchCondition|: Given to |MojoWatch()| to indicate whether the
// watched signals should trigger a notification when becoming satisfied or
// becoming not-satisfied.
//
//   |MOJO_WATCH_CONDITION_NOT_SATISFIED| - A watch added with this setting will
//       trigger a notification when any of the watched signals transition from
//       being not-satisfied to being satisfied.
//   |MOJO_WATCH_CONDITION_SATISFIED| - A watch added with this setting will
//       trigger a notification when any of the watched signals transition from
//       being satisfied to being not-satisfied, or when none of the watched
//       signals can ever be satisfied again.

typedef uint32_t MojoWatchCondition;

#ifdef __cplusplus
const MojoWatchCondition MOJO_WATCH_CONDITION_NOT_SATISFIED = 0;
const MojoWatchCondition MOJO_WATCH_CONDITION_SATISFIED = 1;
#else
#define MOJO_WATCH_CONDITION_NOT_SATISFIED ((MojoWatchCondition)0)
#define MOJO_WATCH_CONDITION_SATISFIED ((MojoWatchCondition)1)
#endif

// |MojoPropertyType|: Property types that can be passed to |MojoGetProperty()|
// to retrieve system properties. May take the following values:
//   |MOJO_PROPERTY_TYPE_SYNC_CALL_ALLOWED| - Whether making synchronous calls
//       (i.e., blocking to wait for a response to an outbound message) is
//       allowed. The property value is of boolean type. If the value is true,
//       users should refrain from making sync calls.
typedef uint32_t MojoPropertyType;

#ifdef __cplusplus
const MojoPropertyType MOJO_PROPERTY_TYPE_SYNC_CALL_ALLOWED = 0;
#else
#define MOJO_PROPERTY_TYPE_SYNC_CALL_ALLOWED ((MojoPropertyType)0)
#endif

#endif  // MOJO_PUBLIC_C_SYSTEM_TYPES_H_