1 files changed, 191 insertions, 54 deletions
diff --git a/src/objective-c/GRPCClient/GRPCCall.h b/src/objective-c/GRPCClient/GRPCCall.h
index 4eda499b1a..5918f8857a 100644
--- a/src/objective-c/GRPCClient/GRPCCall.h
+++ b/src/objective-c/GRPCClient/GRPCCall.h
@@ -31,77 +31,214 @@
  *
  */
 
-// The gRPC protocol is an RPC protocol on top of HTTP2.
-//
-// While the most common type of RPC receives only one request message and returns only one response
-// message, the protocol also supports RPCs that return multiple individual messages in a streaming
-// fashion, RPCs that accept a stream of request messages, or RPCs with both streaming requests and
-// responses.
-//
-// Conceptually, each gRPC call consists of a bidirectional stream of binary messages, with RPCs of
-// the "non-streaming type" sending only one message in the corresponding direction (the protocol
-// doesn't make any distinction).
-//
-// Each RPC uses a different HTTP2 stream, and thus multiple simultaneous RPCs can be multiplexed
-// transparently on the same TCP connection.
+/**
+ * The gRPC protocol is an RPC protocol on top of HTTP2.
+ *
+ * While the most common type of RPC receives only one request message and returns only one response
+ * message, the protocol also supports RPCs that return multiple individual messages in a streaming
+ * fashion, RPCs that accept a stream of request messages, or RPCs with both streaming requests and
+ * responses.
+ *
+ * Conceptually, each gRPC call consists of a bidirectional stream of binary messages, with RPCs of
+ * the "non-streaming type" sending only one message in the corresponding direction (the protocol
+ * doesn't make any distinction).
+ *
+ * Each RPC uses a different HTTP2 stream, and thus multiple simultaneous RPCs can be multiplexed
+ * transparently on the same TCP connection.
+ */
 
 #import <Foundation/Foundation.h>
 #import <RxLibrary/GRXWriter.h>
 
-// Keys used in |NSError|'s |userInfo| dictionary to store the response headers and trailers sent by
-// the server.
+#pragma mark gRPC errors
+
+/** Domain of NSError objects produced by gRPC. */
+extern NSString *const kGRPCErrorDomain;
+
+/**
+ * gRPC error codes.
+ * Note that a few of these are never produced by the gRPC libraries, but are of general utility for
+ * server applications to produce.
+ */
+typedef NS_ENUM(NSUInteger, GRPCErrorCode) {
+  /** The operation was cancelled (typically by the caller). */
+  GRPCErrorCodeCancelled = 1,
+
+  /**
+   * Unknown error. Errors raised by APIs that do not return enough error information may be
+   * converted to this error.
+   */
+  GRPCErrorCodeUnknown = 2,
+
+  /**
+   * The client specified an invalid argument. Note that this differs from FAILED_PRECONDITION.
+   * INVALID_ARGUMENT indicates arguments that are problematic regardless of the state of the
+   * server (e.g., a malformed file name).
+   */
+  GRPCErrorCodeInvalidArgument = 3,
+
+  /**
+   * Deadline expired before operation could complete. For operations that change the state of the
+   * server, this error may be returned even if the operation has completed successfully. For
+   * example, a successful response from the server could have been delayed long enough for the
+   * deadline to expire.
+   */
+  GRPCErrorCodeDeadlineExceeded = 4,
+
+  /** Some requested entity (e.g., file or directory) was not found. */
+  GRPCErrorCodeNotFound = 5,
+
+  /** Some entity that we attempted to create (e.g., file or directory) already exists. */
+  GRPCErrorCodeAlreadyExists = 6,
+
+  /**
+   * The caller does not have permission to execute the specified operation. PERMISSION_DENIED isn't
+   * used for rejections caused by exhausting some resource (RESOURCE_EXHAUSTED is used instead for
+   * those errors). PERMISSION_DENIED doesn't indicate a failure to identify the caller
+   * (UNAUTHENTICATED is used instead for those errors).
+   */
+  GRPCErrorCodePermissionDenied = 7,
+
+  /**
+   * The request does not have valid authentication credentials for the operation (e.g. the caller's
+   * identity can't be verified).
+   */
+  GRPCErrorCodeUnauthenticated = 16,
+
+  /** Some resource has been exhausted, perhaps a per-user quota. */
+  GRPCErrorCodeResourceExhausted = 8,
+
+  /**
+   * The RPC was rejected because the server is not in a state required for the procedure's
+   * execution. For example, a directory to be deleted may be non-empty, etc.
+   * The client should not retry until the server state has been explicitly fixed (e.g. by
+   * performing another RPC). The details depend on the service being called, and should be found in
+   * the NSError's userInfo.
+   */
+  GRPCErrorCodeFailedPrecondition = 9,
+
+  /**
+   * The RPC was aborted, typically due to a concurrency issue like sequencer check failures,
+   * transaction aborts, etc. The client should retry at a higher-level (e.g., restarting a read-
+   * modify-write sequence).
+   */
+  GRPCErrorCodeAborted = 10,
+
+  /**
+   * The RPC was attempted past the valid range. E.g., enumerating past the end of a list.
+   * Unlike INVALID_ARGUMENT, this error indicates a problem that may be fixed if the system state
+   * changes. For example, an RPC to get elements of a list will generate INVALID_ARGUMENT if asked
+   * to return the element at a negative index, but it will generate OUT_OF_RANGE if asked to return
+   * the element at an index past the current size of the list.
+   */
+  GRPCErrorCodeOutOfRange = 11,
+
+  /** The procedure is not implemented or not supported/enabled in this server. */
+  GRPCErrorCodeUnimplemented = 12,
+
+  /**
+   * Internal error. Means some invariant expected by the server application or the gRPC library has
+   * been broken.
+   */
+  GRPCErrorCodeInternal = 13,
+
+  /**
+   * The server is currently unavailable. This is most likely a transient condition and may be
+   * corrected by retrying with a backoff.
+   */
+  GRPCErrorCodeUnavailable = 14,
+
+  /** Unrecoverable data loss or corruption. */
+  GRPCErrorCodeDataLoss = 15,
+};
+
+/**
+ * Keys used in |NSError|'s |userInfo| dictionary to store the response headers and trailers sent by
+ * the server.
+ */
 extern id const kGRPCHeadersKey;
 extern id const kGRPCTrailersKey;
 
-// Represents a single gRPC remote call.
+#pragma mark GRPCCall
+
+/**
+ * The container of the request headers of an RPC conforms to this protocol, which is a subset of
+ * NSMutableDictionary's interface. It will become a NSMutableDictionary later on.
+ * The keys of this container are the header names, which per the HTTP standard are case-
+ * insensitive. They are stored in lowercase (which is how HTTP/2 mandates them on the wire), and
+ * can only consist of ASCII characters.
+ * A header value is a NSString object (with only ASCII characters), unless the header name has the
+ * suffix "-bin", in which case the value has to be a NSData object.
+ */
+@protocol GRPCRequestHeaders <NSObject>
+
+@property(nonatomic, readonly) NSUInteger count;
+
+- (id)objectForKeyedSubscript:(NSString *)key;
+- (void)setObject:(id)obj forKeyedSubscript:(NSString *)key;
+
+- (void)removeAllObjects;
+- (void)removeObjectForKey:(NSString *)key;
+
+@end
+
+/** Represents a single gRPC remote call. */
 @interface GRPCCall : GRXWriter
 
-// These HTTP headers will be passed to the server as part of this call. Each HTTP header is a
-// name-value pair with string names and either string or binary values.
-//
-// The passed dictionary has to use NSString keys, corresponding to the header names. The value
-// associated to each can be a NSString object or a NSData object. E.g.:
-//
-// call.requestHeaders = @{@"authorization": @"Bearer ..."};
-//
-// call.requestHeaders[@"my-header-bin"] = someData;
-//
-// After the call is started, trying to modify this property is an error.
-//
-// For convenience, the property is initialized to an empty NSMutableDictionary, and the setter
-// accepts (and copies) both mutable and immutable dictionaries.
-- (NSMutableDictionary *)requestHeaders; // nonatomic
-- (void)setRequestHeaders:(NSDictionary *)requestHeaders; // nonatomic, copy
-
-// This dictionary is populated with the HTTP headers received from the server. This happens before
-// any response message is received from the server. It has the same structure as the request
-// headers dictionary: Keys are NSString header names; names ending with the suffix "-bin" have a
-// NSData value; the others have a NSString value.
-//
-// The value of this property is nil until all response headers are received, and will change before
-// any of -writeValue: or -writesFinishedWithError: are sent to the writeable.
+/**
+ * These HTTP headers will be passed to the server as part of this call. Each HTTP header is a
+ * name-value pair with string names and either string or binary values.
+ *
+ * The passed dictionary has to use NSString keys, corresponding to the header names. The value
+ * associated to each can be a NSString object or a NSData object. E.g.:
+ *
+ * call.requestHeaders = @{@"authorization": @"Bearer ..."};
+ *
+ * call.requestHeaders[@"my-header-bin"] = someData;
+ *
+ * After the call is started, trying to modify this property is an error.
+ *
+ * The property is initialized to an empty NSMutableDictionary.
+ */
+@property(atomic, readonly) id<GRPCRequestHeaders> requestHeaders;
+
+/**
+ * This dictionary is populated with the HTTP headers received from the server. This happens before
+ * any response message is received from the server. It has the same structure as the request
+ * headers dictionary: Keys are NSString header names; names ending with the suffix "-bin" have a
+ * NSData value; the others have a NSString value.
+ *
+ * The value of this property is nil until all response headers are received, and will change before
+ * any of -writeValue: or -writesFinishedWithError: are sent to the writeable.
+ */
 @property(atomic, readonly) NSDictionary *responseHeaders;
 
-// Same as responseHeaders, but populated with the HTTP trailers received from the server before the
-// call finishes.
-//
-// The value of this property is nil until all response trailers are received, and will change
-// before -writesFinishedWithError: is sent to the writeable.
+/**
+ * Same as responseHeaders, but populated with the HTTP trailers received from the server before the
+ * call finishes.
+ *
+ * The value of this property is nil until all response trailers are received, and will change
+ * before -writesFinishedWithError: is sent to the writeable.
+ */
 @property(atomic, readonly) NSDictionary *responseTrailers;
 
-// The request writer has to write NSData objects into the provided Writeable. The server will
-// receive each of those separately and in order as distinct messages.
-// A gRPC call might not complete until the request writer finishes. On the other hand, the request
-// finishing doesn't necessarily make the call to finish, as the server might continue sending
-// messages to the response side of the call indefinitely (depending on the semantics of the
-// specific remote method called).
-// To finish a call right away, invoke cancel.
+/**
+ * The request writer has to write NSData objects into the provided Writeable. The server will
+ * receive each of those separately and in order as distinct messages.
+ * A gRPC call might not complete until the request writer finishes. On the other hand, the request
+ * finishing doesn't necessarily make the call to finish, as the server might continue sending
+ * messages to the response side of the call indefinitely (depending on the semantics of the
+ * specific remote method called).
+ * To finish a call right away, invoke cancel.
+ */
 - (instancetype)initWithHost:(NSString *)host
                         path:(NSString *)path
               requestsWriter:(GRXWriter *)requestsWriter NS_DESIGNATED_INITIALIZER;
 
-// Finishes the request side of this call, notifies the server that the RPC should be cancelled, and
-// finishes the response side of the call with an error of code CANCELED.
+/**
+ * Finishes the request side of this call, notifies the server that the RPC should be cancelled, and
+ * finishes the response side of the call with an error of code CANCELED.
+ */
 - (void)cancel;
 
 // TODO(jcanizales): Let specify a deadline. As a category of GRXWriter?