[Crash] CZWebImage Crash - caused by CZHttpFile.WriteFile threadsafety.

[geekaurora]

Description

CZGithubAppKit - CZWebImage Crash (Force quit 5 times: Data = empty)(First page)

Reason

• data is empty (non-nil): so can't be transformed to image = nil: triggers assertion
  • Same image downloads: Same URL not cancelled

Details

Write to file wasn't atomic, and no ioQueue.async(flags: .barrier):

In CZDiskCacheManager.setCacheFile(),
data.write(to: fileURL) should be data.write(to: fileURL, options: [.atomic]).

Solution

In CZDiskCacheManager.setCacheFile(),

• Data.write: atomic
• ioQueue.async(flags: .barrier): will cause performance issue as many image files are being written to disk when scrolling. (it was ioQueue.async(flags: .barrier), removed for performance reason) - [Won't Fix][P2][Performance] CZDiskCacheManager.setCacheFile() - WriteFile threadsafety ioQueue.async(flags: .barrier) #38

Others

• cleanDiskCacheIfNeeded() - only if shouldEnableCachedItemsDict is true.