proto: introduce error injections

This patch introduces error injections to internal API.

Needed for tarantool/aeon#502

Author: ImeevMA

aeon_internal.proto

@@ -16,6 +16,16 @@ service InternalService {
   rpc FindRange(FindRangeRequest) returns (FindRangeResponse) {}
   // Update space cache.
   rpc UpdateCache(UpdateCacheRequest) returns (UpdateCacheResponse) {}
+  // Set error injection.
+  rpc InjectionSet(InjectionSetRequest) returns (InjectionSetResponse) {}
+  // Clear error injection.
+  rpc InjectionClear(InjectionClearRequest) returns (InjectionClearResponse) {}
+  // Check if error injection is set.
+  rpc InjectionIsSet(InjectionIsSetRequest) returns (InjectionIsSetResponse) {}
+  // Get injection error, if it is set.
+  rpc InjectError(InjectErrorRequest) returns (InjectErrorResponse) {}
+  // Wait until the injection error is cleared, if one is set.
+  rpc InjectDelay(InjectDelayRequest) returns (InjectDelayResponse) {}
 }
 
 // Description of a range.
@@ -122,3 +132,54 @@ message UpdateCacheResponse {
   // Error information. Set only on failure.
   Error error = 1;
 }
+
+// Set error injection.
+
+message InjectionSetRequest {
+  // Name of error injection.
+  string name = 1;
+}
+
+message InjectionSetResponse {}
+
+// Clear error injection.
+
+message InjectionClearRequest {
+  // Name of error injection.
+  string name = 1;
+}
+
+message InjectionClearResponse {}
+
+// Check if error injection is set.
+
+message InjectionIsSetRequest {
+  // Name of error injection.
+  string name = 1;
+}
+
+message InjectionIsSetResponse {
+  // True if error injection is set, false otherwise.
+  bool is_set = 1;
+}
+
+// Get injection error, if it is set.
+
+message InjectErrorRequest {
+  // Name of error injection.
+  string name = 1;
+}
+
+message InjectErrorResponse {
+  // Name of error injection.
+  Error error = 1;
+}
+
+// Wait until the injection error is cleared, if one is set.
+
+message InjectDelayRequest {
+  // Name of error injection.
+  string name = 1;
+}
+
+message InjectDelayResponse {}