robustness fixes plus improve support for auxillary commands so we could run tcl tests.

GETRANGE - fix out of bounds bug.
Add a decorator for "config get"
Add a decorator for "function flush"

README.md

@@ -223,7 +223,6 @@ API 2.0
   - [ ] SCRIPT DEBUG/KILL/FLUSH/EXISTS
 - [X] Set Family
   - [X] SSCAN
-  - [X] SMISMEMBER
 - [X] Sorted Set Family
   - [ ] ZCOUNT
   - [ ] ZINTERSTORE
@@ -258,6 +257,7 @@ exact use-cases for this API.
  - [X] ROLE (2.8) decorator for for master withour replicas
  - [X] UNLINK (4.0) decorator for DEL command
  - [X] BGSAVE
+ - [X] FUNCTION FLUSH
 ## Milestone Nymph
 API 2,3,4 without cluster support, without modules, without memory inspection commands.
 Without support for keyspace notifications.

doc/differences.md

@@ -0,0 +1,12 @@
+# Differences with Redis
+
+## String lengths, indices.
+
+String sizes are limited to 256MB.
+Indices (say in GETRANGE and SETRANGE commands) should be signed 32 bit integers in range
+[-2147483647, 2147483648].
+
+## Expiry ranges.
+Expirations are limited to 365 days. For commands with millisecond precision like PEXPIRE or PSETEX,
+expirations greater than 2^25ms are quietly rounded to the nearest second loosing precision of ~0.002%.
+

src/server/main_service.cc

@@ -937,6 +937,20 @@ void Service::Unsubscribe(CmdArgList args, ConnectionContext* cntx) {
   cntx->ChangeSubscription(false, true, std::move(args));
 }
 
+// Not a real implementation. Serves as a decorator to accept some function commands
+// for testing.
+void Service::Function(CmdArgList args, ConnectionContext* cntx) {
+  ToUpper(&args[1]);
+  string_view sub_cmd = ArgS(args, 1);
+
+  if (sub_cmd == "FLUSH") {
+    return (*cntx)->SendOk();
+  }
+
+  string err = absl::StrCat("Unknown subcommand '", sub_cmd, "'. Try FUNCTION HELP.");
+  return (*cntx)->SendError(err, kSyntaxErr);
+}
+
 VarzValue::Map Service::GetVarzStats() {
   VarzValue::Map res;
 
@@ -963,13 +977,14 @@ void Service::RegisterCommands() {
 
   registry_ << CI{"QUIT", CO::READONLY | CO::FAST, 1, 0, 0, 0}.HFUNC(Quit)
             << CI{"MULTI", CO::NOSCRIPT | CO::FAST | CO::LOADING, 1, 0, 0, 0}.HFUNC(Multi)
-            << CI{"DISCARD", CO::NOSCRIPT | CO::FAST| CO::LOADING, 1, 0, 0, 0}.MFUNC(Discard)
+            << CI{"DISCARD", CO::NOSCRIPT | CO::FAST | CO::LOADING, 1, 0, 0, 0}.MFUNC(Discard)
             << CI{"EVAL", CO::NOSCRIPT, -3, 0, 0, 0}.MFUNC(Eval).SetValidator(&EvalValidator)
             << CI{"EVALSHA", CO::NOSCRIPT, -3, 0, 0, 0}.MFUNC(EvalSha).SetValidator(&EvalValidator)
             << CI{"EXEC", kExecMask, 1, 0, 0, 0}.MFUNC(Exec)
             << CI{"PUBLISH", CO::LOADING | CO::FAST, 3, 0, 0, 0}.MFUNC(Publish)
             << CI{"SUBSCRIBE", CO::NOSCRIPT | CO::LOADING, -2, 0, 0, 0}.MFUNC(Subscribe)
-            << CI{"UNSUBSCRIBE", CO::NOSCRIPT | CO::LOADING, -2, 0, 0, 0}.MFUNC(Unsubscribe);
+            << CI{"UNSUBSCRIBE", CO::NOSCRIPT | CO::LOADING, -2, 0, 0, 0}.MFUNC(Unsubscribe)
+            << CI{"FUNCTION", CO::NOSCRIPT, 2, 0, 0, 0}.MFUNC(Function);
 
   StringFamily::Register(&registry_);
   GenericFamily::Register(&registry_);

src/server/main_service.h

@@ -78,6 +78,7 @@ class Service : public facade::ServiceInterface {
   void Publish(CmdArgList args, ConnectionContext* cntx);
   void Subscribe(CmdArgList args, ConnectionContext* cntx);
   void Unsubscribe(CmdArgList args, ConnectionContext* cntx);
+  void Function(CmdArgList args, ConnectionContext* cntx);
 
   struct EvalArgs {
     std::string_view sha;  // only one of them is defined.

src/server/server_family.cc

@@ -245,6 +245,11 @@ void ServerFamily::Config(CmdArgList args, ConnectionContext* cntx) {
 
   if (sub_cmd == "SET") {
     return (*cntx)->SendOk();
+  } else if (sub_cmd == "GET" && args.size() == 3) {
+    string_view param = ArgS(args, 2);
+    string_view res[2] = {param, "tbd"};
+
+    return (*cntx)->SendStringArr(res);
   } else {
     string err = absl::StrCat("Unknown subcommand or wrong number of arguments for '", sub_cmd,
                               "'. Try CONFIG HELP.");

src/server/set_family_test.cc

@@ -64,6 +64,9 @@ TEST_F(SetFamilyTest, SDiff) {
   resp = Run({"sdiffstore", "a", "b", "c"});
   EXPECT_THAT(resp[0], IntArg(3));
 
+  Run({"set", "str", "foo"});
+  EXPECT_THAT(Run({"sdiff", "b", "str"}), ElementsAre(ErrArg("WRONGTYPE ")));
+
   Run({"sadd", "bar", "x", "a", "b", "c"});
   Run({"sadd", "foo", "c"});
   Run({"sadd", "car", "a", "d"});

src/server/string_family.cc

@@ -514,26 +514,26 @@ void StringFamily::GetRange(CmdArgList args, ConnectionContext* cntx) {
     if (!it_res.ok())
       return it_res.status();
 
-    if (start < 0 && end < 0 && start > end) {
-      return OpStatus::OK;
-    }
     const CompactObj& co = it_res.value()->second;
     size_t strlen = co.Size();
 
     if (start < 0)
       start = strlen + start;
-    else if (size_t(start) >= strlen)
-      return OpStatus::OK;
-
     if (end < 0)
       end = strlen + end;
 
+    if (strlen == 0 || start > end || size_t(start) >= strlen) {
+      return OpStatus::OK;
+    }
+
     if (start < 0)
       start = 0;
     if (end < 0)
       end = 0;
+
     if (size_t(end) >= strlen)
       end = strlen - 1;
+
     string tmp;
     string_view slice = co.GetSlice(&tmp);
 

src/server/string_family_test.cc

@@ -267,6 +267,8 @@ TEST_F(StringFamilyTest, SetEx) {
 
 TEST_F(StringFamilyTest, Range) {
   Run({"set", "key1", "Hello World"});
+  EXPECT_THAT(Run({"getrange", "key1", "5", "3"}), RespEq(""));
+
   Run({"SETRANGE", "key1", "6", "Earth"});
   EXPECT_THAT(Run({"get", "key1"}), RespEq("Hello Earth"));