[PATCH] D52503: [clangd] More precise index memory usage estimate

[Eric Liu via Phabricator via cfe-commits]

ioeric added inline comments.


================
Comment at: clang-tools-extra/clangd/index/dex/Dex.cpp:251
   Bytes += InvertedIndex.getMemorySize();
-  for (const auto &P : InvertedIndex)
-    Bytes += P.second.bytes();
+  for (const auto &TokenToPostingList : InvertedIndex)
+    Bytes += TokenToPostingList.first.Data.size() +
----------------
kbobyrev wrote:
> ioeric wrote:
> > Would `InvertedIndex.getMemorySize()` be a better estimate?
> IIUC this is only precise for the objects which do not make any allocations (e.g. `std::vector` and `std::string` memory estimate would not be "correct").
> 
> From the documentation
> 
> > This is just the raw memory used by DenseMap. If entries are pointers to objects, the size of the referenced objects are not included.
> 
> I also have `Bytes += InvertedIndex.getMemorySize();` above, so the purpose of this code would be to take into account the size of these "reference objects".
> 
> However, since `PostingList::bytes()` also returns underlying `std::vector` size, this code will probably add these `std::vector` objects size twice (the first one was in `InvertedIndex.getMemorySize()`). I should fix that.
> `If entries are pointers to objects, the size of the referenced objects are not included.`
This applies to *pointers* to objects, but the `PostingList`s in InvertedList are not pointerd? So it seems to me that `InvertedIndex.getMemorySize()` covers everything in the `InvertedIndex`. One way to verify is probably check the size calculated with loop against `InvertedIndex.getMemorySize()`.


https://reviews.llvm.org/D52503