5 ms·

You also need to handle all corner cases where one of the intermediary diffs gets corrupted (you can't generally assume in a program like Firefox that data you

by gcp 10y ago

You also need to handle all corner cases where one of the intermediary diffs gets corrupted (you can't generally assume in a program like Firefox that data you write out is going to be readable in the future because lol common hardware). Or where the diffs are larger than a fresh snapshot. And you absolutely can't get it wrong. It's something that sounds easy until you actually try to get it coded up and shipping. I explained below that this thing isn't a factor for Android because the program gets suspended.

fulafel 10y ago
Firefox does generally assume that the filesystem is reliable (as long as you use fsync properly etc). Witness eg its reliance on SQLite for data storage.
- gcp 10y ago
  SQLite is used exactly because it is so robust even on bad hardware. And you still need to check the data that SQLite is giving you.
  - cbhl 10y ago
    Until you have a NFS homedir...
    - derefr 10y ago
      On the other hand, SQLite with concurrent local and SSHFS-remote updates (where the SSHFS server is run with caching disabled) is entirely stable.
      - alphapapa 10y ago
        I'm curious, could you expand on this comment? Do you mean that you run Firefox from a profile loaded over SSHFS? I can only imagine that being unbearably slow because of I/O latency. And shouldn't disabling caching in SSHFS make it much, much worse?
    - Dylan16807 10y ago
      Does the lack of proper locking on NFS matter when you're only running a single instance of firefox?
Dylan16807 10y ago
In the general case that's a huge pain. In this case, where you're writing a single blob to disk, you can stick a checksum at the end and you're good to go.
- gcp 10y ago
  If you read the bug discussion, you'll see this is one of the most problematic parts.
  - Dylan16807 10y ago
    This bug? https://bugzilla.mozilla.org/show_bug.cgi?id=1304389 https://bugzilla.mozilla.org/show_bug.cgi?id=1304389 It doesn't talk about the difficulties in getting data safely to disk. There's just a worry that taking a hash of the entire session state is expensive. I'm skeptical that a fast hash would take long compared to the time spent serializing to JSON in the first place, let alone time spent diffing.
chris_wot 10y ago
As Microsoft have discovered in their binary patches through Windows update. If you've ever run sfc /scannow and then dism /online /cleanup-image /scanhealth then you are almost certainly seeing corrupted binary patches.

by gcp 10y ago

fulafel 10y ago

Firefox does generally assume that the filesystem is reliable (as long as you use fsync properly etc). Witness eg its reliance on SQLite for data storage.

gcp 10y ago
SQLite is used exactly because it is so robust even on bad hardware. And you still need to check the data that SQLite is giving you.
- cbhl 10y ago
  Until you have a NFS homedir...
  - derefr 10y ago
    On the other hand, SQLite with concurrent local and SSHFS-remote updates (where the SSHFS server is run with caching disabled) is entirely stable.
    - alphapapa 10y ago
      I'm curious, could you expand on this comment? Do you mean that you run Firefox from a profile loaded over SSHFS? I can only imagine that being unbearably slow because of I/O latency. And shouldn't disabling caching in SSHFS make it much, much worse?
  - Dylan16807 10y ago
    Does the lack of proper locking on NFS matter when you're only running a single instance of firefox?

Dylan16807 10y ago

In the general case that's a huge pain. In this case, where you're writing a single blob to disk, you can stick a checksum at the end and you're good to go.

gcp 10y ago
If you read the bug discussion, you'll see this is one of the most problematic parts.
- Dylan16807 10y ago
  This bug? https://bugzilla.mozilla.org/show_bug.cgi?id=1304389 https://bugzilla.mozilla.org/show_bug.cgi?id=1304389 It doesn't talk about the difficulties in getting data safely to disk. There's just a worry that taking a hash of the entire session state is expensive. I'm skeptical that a fast hash would take long compared to the time spent serializing to JSON in the first place, let alone time spent diffing.

chris_wot 10y ago

As Microsoft have discovered in their binary patches through Windows update. If you've ever run sfc /scannow and then dism /online /cleanup-image /scanhealth then you are almost certainly seeing corrupted binary patches.