Add reply_schema to command json files (internal for now) (#10273)

Work in progress towards implementing a reply schema as part of COMMAND DOCS, see #9845
Since ironing the details of the reply schema of each and every command can take a long time, we
would like to merge this PR when the infrastructure is ready, and let this mature in the unstable branch.
Meanwhile the changes of this PR are internal, they are part of the repo, but do not affect the produced build.

### Background
In #9656 we add a lot of information about Redis commands, but we are missing information about the replies

### Motivation
1. Documentation. This is the primary goal.
2. It should be possible, based on the output of COMMAND, to be able to generate client code in typed
  languages. In order to do that, we need Redis to tell us, in detail, what each reply looks like.
3. We would like to build a fuzzer that verifies the reply structure (for now we use the existing
  testsuite, see the "Testing" section)

### Schema
The idea is to supply some sort of schema for the various replies of each command.
The schema will describe the conceptual structure of the reply (for generated clients), as defined in RESP3.
Note that the reply structure itself may change, depending on the arguments (e.g. `XINFO STREAM`, with
and without the `FULL` modifier)
We decided to use the standard json-schema (see https://json-schema.org/) as the reply-schema.

Example for `BZPOPMIN`:
```
"reply_schema": {
    "oneOf": [
        {
            "description": "Timeout reached and no elements were popped.",
            "type": "null"
        },
        {
            "description": "The keyname, popped member, and its score.",
            "type": "array",
            "minItems": 3,
            "maxItems": 3,
            "items": [
                {
                    "description": "Keyname",
                    "type": "string"
                },
                {
                    "description": "Member",
                    "type": "string"
                },
                {
                    "description": "Score",
                    "type": "number"
                }
            ]
        }
    ]
}
```

#### Notes
1.  It is ok that some commands' reply structure depends on the arguments and it's the caller's responsibility
  to know which is the relevant one. this comes after looking at other request-reply systems like OpenAPI,
  where the reply schema can also be oneOf and the caller is responsible to know which schema is the relevant one.
2. The reply schemas will describe RESP3 replies only. even though RESP3 is structured, we want to use reply
  schema for documentation (and possibly to create a fuzzer that validates the replies)
3. For documentation, the description field will include an explanation of the scenario in which the reply is sent,
  including any relation to arguments. for example, for `ZRANGE`'s two schemas we will need to state that one
  is with `WITHSCORES` and the other is without.
4. For documentation, there will be another optional field "notes" in which we will add a short description of
  the representation in RESP2, in case it's not trivial (RESP3's `ZRANGE`'s nested array vs. RESP2's flat
  array, for example)

Given the above:
1. We can generate the "return" section of all commands in [redis-doc](https://redis.io/commands/)
  (given that "description" and "notes" are comprehensive enough)
2. We can generate a client in a strongly typed language (but the return type could be a conceptual
  `union` and the caller needs to know which schema is relevant). see the section below for RESP2 support.
3. We can create a fuzzer for RESP3.

### Limitations (because we are using the standard json-schema)
The problem is that Redis' replies are more diverse than what the json format allows. This means that,
when we convert the reply to a json (in order to validate the schema against it), we lose information (see
the "Testing" section below).
The other option would have been to extend the standard json-schema (and json format) to include stuff
like sets, bulk-strings, error-string, etc. but that would mean also extending the schema-validator - and that
seemed like too much work, so we decided to compromise.

Examples:
1. We cannot tell the difference between an "array" and a "set"
2. We cannot tell the difference between simple-string and bulk-string
3. we cannot verify true uniqueness of items in commands like ZRANGE: json-schema doesn't cover the
  case of two identical members with different scores (e.g. `[["m1",6],["m1",7]]`) because `uniqueItems`
  compares (member,score) tuples and not just the member name. 

### Testing
This commit includes some changes inside Redis in order to verify the schemas (existing and future ones)
are indeed correct (i.e. describe the actual response of Redis).
To do that, we added a debugging feature to Redis that causes it to produce a log of all the commands
it executed and their replies.
For that, Redis needs to be compiled with `-DLOG_REQ_RES` and run with
`--reg-res-logfile <file> --client-default-resp 3` (the testsuite already does that if you run it with
`--log-req-res --force-resp3`)
You should run the testsuite with the above args (and `--dont-clean`) in order to make Redis generate
`.reqres` files (same dir as the `stdout` files) which contain request-response pairs.
These files are later on processed by `./utils/req-res-log-validator.py` which does:
1. Goes over req-res files, generated by redis-servers, spawned by the testsuite (see logreqres.c)
2. For each request-response pair, it validates the response against the request's reply_schema
  (obtained from the extended COMMAND DOCS)
5. In order to get good coverage of the Redis commands, and all their different replies, we chose to use
  the existing redis test suite, rather than attempt to write a fuzzer.

#### Notes about RESP2
1. We will not be able to use the testing tool to verify RESP2 replies (we are ok with that, it's time to
  accept RESP3 as the future RESP)
2. Since the majority of the test suite is using RESP2, and we want the server to reply with RESP3
  so that we can validate it, we will need to know how to convert the actual reply to the one expected.
   - number and boolean are always strings in RESP2 so the conversion is easy
   - objects (maps) are always a flat array in RESP2
   - others (nested array in RESP3's `ZRANGE` and others) will need some special per-command
     handling (so the client will not be totally auto-generated)

Example for ZRANGE:
```
"reply_schema": {
    "anyOf": [
        {
            "description": "A list of member elements",
            "type": "array",
            "uniqueItems": true,
            "items": {
                "type": "string"
            }
        },
        {
            "description": "Members and their scores. Returned in case `WITHSCORES` was used.",
            "notes": "In RESP2 this is returned as a flat array",
            "type": "array",
            "uniqueItems": true,
            "items": {
                "type": "array",
                "minItems": 2,
                "maxItems": 2,
                "items": [
                    {
                        "description": "Member",
                        "type": "string"
                    },
                    {
                        "description": "Score",
                        "type": "number"
                    }
                ]
            }
        }
    ]
}
```

### Other changes
1. Some tests that behave differently depending on the RESP are now being tested for both RESP,
  regardless of the special log-req-res mode ("Pub/Sub PING" for example)
2. Update the history field of CLIENT LIST
3. Added basic tests for commands that were not covered at all by the testsuite

### TODO

- [x] (maybe a different PR) add a "condition" field to anyOf/oneOf schemas that refers to args. e.g.
  when `SET` return NULL, the condition is `arguments.get||arguments.condition`, for `OK` the condition
  is `!arguments.get`, and for `string` the condition is `arguments.get` - https://github.com/redis/redis/issues/11896
- [x] (maybe a different PR) also run `runtest-cluster` in the req-res logging mode
- [x] add the new tests to GH actions (i.e. compile with `-DLOG_REQ_RES`, run the tests, and run the validator)
- [x] (maybe a different PR) figure out a way to warn about (sub)schemas that are uncovered by the output
  of the tests - https://github.com/redis/redis/issues/11897
- [x] (probably a separate PR) add all missing schemas
- [x] check why "SDOWN is triggered by misconfigured instance replying with errors" fails with --log-req-res
- [x] move the response transformers to their own file (run both regular, cluster, and sentinel tests - need to
  fight with the tcl including mechanism a bit)
- [x] issue: module API - https://github.com/redis/redis/issues/11898
- [x] (probably a separate PR): improve schemas: add `required` to `object`s - https://github.com/redis/redis/issues/11899

Co-authored-by: Ozan Tezcan <ozantezcan@gmail.com>
Co-authored-by: Hanna Fadida <hanna.fadida@redislabs.com>
Co-authored-by: Oran Agra <oran@redislabs.com>
Co-authored-by: Shaya Potter <shaya@redislabs.com>

1 files changed, 74 insertions, 23 deletions

diff --git a/src/server.h b/src/server.h
index 36cd8c760..056123d0f 100644
--- a/src/server.h
+++ b/src/server.h
@@ -1101,6 +1101,31 @@ typedef struct {
     size_t mem_usage_sum;
 } clientMemUsageBucket;
 
+#ifdef LOG_REQ_RES
+/* Structure used to log client's requests and their
+ * responses (see logreqres.c) */
+typedef struct {
+    /* General */
+    int argv_logged; /* 1 if the command was logged */
+    /* Vars for log buffer */
+    unsigned char *buf; /* Buffer holding the data (request and response) */
+    size_t used;
+    size_t capacity;
+    /* Vars for offsets within the client's reply */
+    struct {
+        /* General */
+        int saved; /* 1 if we already saved the offset (first time we call addReply*) */
+        /* Offset within the static reply buffer */
+        int bufpos;
+        /* Offset within the reply block list */
+        struct {
+            int index;
+            size_t used;
+        } last_node;
+    } offset;
+} clientReqResInfo;
+#endif
+
 typedef struct client {
     uint64_t id;            /* Client incremental unique ID. */
     uint64_t flags;         /* Client flags: CLIENT_* macros. */
@@ -1212,6 +1237,9 @@ typedef struct client {
     int bufpos;
     size_t buf_usable_size; /* Usable size of buffer. */
     char *buf;
+#ifdef LOG_REQ_RES
+    clientReqResInfo reqres;
+#endif
 } client;
 
 /* ACL information */
@@ -1540,6 +1568,11 @@ struct redisServer {
     client *current_client;     /* The client that triggered the command execution (External or AOF). */
     client *executing_client;   /* The client executing the current command (possibly script or module). */
 
+#ifdef LOG_REQ_RES
+    char *req_res_logfile; /* Path of log file for logging all requests and their replies. If NULL, no logging will be performed */
+    unsigned int client_default_resp;
+#endif
+
     /* Stuff for client mem eviction */
     clientMemUsageBucket* client_mem_usage_buckets;
 
@@ -2106,30 +2139,38 @@ typedef struct redisCommandArg {
     int num_args;
 } redisCommandArg;
 
-/* Must be synced with RESP2_TYPE_STR and generate-command-code.py */
-typedef enum {
-    RESP2_SIMPLE_STRING,
-    RESP2_ERROR,
-    RESP2_INTEGER,
-    RESP2_BULK_STRING,
-    RESP2_NULL_BULK_STRING,
-    RESP2_ARRAY,
-    RESP2_NULL_ARRAY,
-} redisCommandRESP2Type;
-
-/* Must be synced with RESP3_TYPE_STR and generate-command-code.py */
+#ifdef LOG_REQ_RES
+
+/* Must be synced with generate-command-code.py */
 typedef enum {
-    RESP3_SIMPLE_STRING,
-    RESP3_ERROR,
-    RESP3_INTEGER,
-    RESP3_DOUBLE,
-    RESP3_BULK_STRING,
-    RESP3_ARRAY,
-    RESP3_MAP,
-    RESP3_SET,
-    RESP3_BOOL,
-    RESP3_NULL,
-} redisCommandRESP3Type;
+    JSON_TYPE_STRING,
+    JSON_TYPE_INTEGER,
+    JSON_TYPE_BOOLEAN,
+    JSON_TYPE_OBJECT,
+    JSON_TYPE_ARRAY,
+} jsonType;
+
+typedef struct jsonObjectElement {
+    jsonType type;
+    const char *key;
+    union {
+        const char *string;
+        long long integer;
+        int boolean;
+        struct jsonObject *object;
+        struct {
+            struct jsonObject **objects;
+            int length;
+        } array;
+    } value;
+} jsonObjectElement;
+
+typedef struct jsonObject {
+    struct jsonObjectElement *elements;
+    int length;
+} jsonObject;
+
+#endif
 
 /* WARNING! This struct must match RedisModuleCommandHistoryEntry */
 typedef struct {
@@ -2280,6 +2321,10 @@ struct redisCommand {
     struct redisCommand *subcommands;
     /* Array of arguments (may be NULL) */
     struct redisCommandArg *args;
+#ifdef LOG_REQ_RES
+    /* Reply schema */
+    struct jsonObject *reply_schema;
+#endif
 
     /* Runtime populated data */
     long long microseconds, calls, rejected_calls, failed_calls;
@@ -2587,6 +2632,12 @@ client *lookupClientByID(uint64_t id);
 int authRequired(client *c);
 void putClientInPendingWriteQueue(client *c);
 
+/* logreqres.c - logging of requests and responses */
+void reqresReset(client *c, int free_buf);
+void reqresSaveClientReplyOffset(client *c);
+size_t reqresAppendRequest(client *c);
+size_t reqresAppendResponse(client *c);
+
 #ifdef __GNUC__
 void addReplyErrorFormatEx(client *c, int flags, const char *fmt, ...)
     __attribute__((format(printf, 3, 4)));