MMKV.mmkvWithID crash

[rednels]

MMKV.mmkvWithID("test/hello2").encode("hello", "world")

id中使用/会导致崩溃

[lingol]

Well, MMKV uses id as filename. For the time being, just don't do this.

[rednels]

Why not Hash Code or MD5

[lingol]

Why not Hash Code or MD5

It's already shipped. Now is too late for that. That's why.

[ysbing]

Why not Hash Code or MD5

It's already shipped. Now is too late for that. That's why.

Is it possible to encode only special characters?

[lingol]

Is it possible to encode only special characters?

Or just throw exception on bad id?

Encoding special char is always complicated. Say you replaces / with _, now how do you handle normal _? With __? Now don't forget there may already be some id that has an _, how do you handle old id?

[zhongwuzw]

Is this related to Android? I don't familiar with it, butI think we can find the issue character and just encode it, the way like encodeURI which transform certain characters using escape sequences.

[lingol]

Is this related to Android? I don't familiar with it, butI think we can find the issue character and just encode it, the way like encodeURI which transform certain characters using escape sequences.

No. It has nothing to do with Android. All those ecodeXXX has the same problem I described before: they don't support backward compatibility.

[lingol]

Is it possible to encode only special characters?

Or just throw exception on bad id?

Fixed with commit.

[ysbing]

Other char?

[lingol]

Other char?

Hmm...

[zhongwuzw]

@lingol

No. It has nothing to do with Android. All those ecodeXXX has the same problem I described before: they don't support backward compatibility.

No backward compatible? I think it compatible, previously it would crash, after encode specific char, it works.

[lingol]

No backward compatible? I think it compatible, previously it would crash, after encode specific char, it works.

Encoding special char is always complicated. Say you replaces / with _, now how do you handle normal _? With __? Now don't forget there may already be some id that has an _, how do you handle old id?

Had I not been clear? Those encodeXXX algorithms, no matter which char(s) they choose to escape, are choosing valid chars to escape with. And how do they handle these valid chars themself? They do double escape. That's where the No backward compatible happens.

[zhongwuzw]

@lingol First, scan the mmkvID, if it exist special character (which leads to crash), encode it and using a separate sub-directory in directory mmkv to store these files which have special characters. If it not have special character, keep the regular way.

[lingol]

@zhongwuzw

Say we replace / with _.

Given test/hello2, we get test_hello2, right? Everything goes well. Except if there is some one already create a MMKV instance with test_hello2.

Now tell me, how do you handle this collision?

[zhongwuzw]

@lingol Emm, maybe you don't get what I point 😂 . I'll explain further, as your example, if given test/hello2, we find it contains special character /, so we encode it to test_hello2, and besides this, we add a separate subdirectory to store the file, so file would be stored in mmkv/special-character/ directory (PS. for id which not contains special character, we still store the files in mmkv/ directory). So no collision would be happen.

[ajinwu]

what? are you sure Sent from Meizu M5 Note

…

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[lingol]

@zhongwuzw That might just work. Would you like to write a pr?

[zhongwuzw]

@lingol Yeah, I can, but firstly, I need to confirm something because I'm not familiar Android, the reason which causes crash is the file cannot created? because intermediate directories not exist if id contains /? If it is, I think we only need to modify implementation mappedKVPathWithID and crcPathWithID, and judge wether contains /, if existed, encode it and create a separate sub-directory, am I right?

[lingol]

Other char?

@zhongwuzw Not just /.

[lingol]

Release with v1.0.13.