jlfwong/speedscope
1
1
Fork 0
mirror of https://github.com/jlfwong/speedscope.git synced 2024-11-22 12:53:23 +03:00
Code Issues Projects Releases Wiki Activity

Clarify magic numbers in getRawSampleList

Browse Source
This commit is contained in:
Jamie Wong 2019-03-10 23:27:15 -07:00
parent e318f63fd2
commit 0235594002
1 changed files with 9 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
src/import/instruments.ts
View File

@ -278,13 +278,21 @@ async function getRawSampleList(core: TraceDirectoryTree): Promise<Sample[]> {
while (true) {
// Schema as of Instruments 8.3.3 is a 6 byte timestamp, followed by a bunch
// of stuff we don't care about, followed by a 4 byte backtrace ID
const timestampBytes = 48 / 8
const timestamp = bulkstore.readUint48()
if (timestamp === 0) break
const threadIDBytes = 32 / 8
const threadID = bulkstore.readUint32()
bulkstore.skip(bytesPerEntry - 6 - 4 - 4)
// Skip the stuff we don't care about. We can do this because we know how
// many bytes there shuold be per entry from the header of the file, and
// we know how many bytes we're reading for each of the fields we do care
// about.
const backtraceIDBytes = 32 / 8
bulkstore.skip(bytesPerEntry - timestampBytes - threadIDBytes - backtraceIDBytes)
const backtraceID = bulkstore.readUint32()
samples.push({timestamp, threadID, backtraceID})
}
return samples