Half-finished attempt at allowing older, non-meta profiles too

I'm not sure it's worth the complexity

src/PProf.jl

@@ -97,14 +97,16 @@ function pprof(data::Union{Nothing, Vector{UInt}} = nothing,
                keep_frames::Union{Nothing, AbstractString} = nothing,
                ui_relative_percentages::Bool = true,
             )
+    has_meta = false
     if data === nothing
         data = if isdefined(Profile, :has_meta)
             copy(Profile.fetch(include_meta = true))
+            has_meta = true
         else
             copy(Profile.fetch())
         end
     elseif isdefined(Profile, :has_meta)
-        @assert Profile.has_meta(data) "PProf expects `Profile.fetch(include_meta=true)`."
+        has_meta = Profile.has_meta(data)
     end
     lookup = lidict
     if lookup === nothing
@@ -147,27 +149,28 @@ function pprof(data::Union{Nothing, Vector{UInt}} = nothing,
     # start decoding backtraces
     location_id = Vector{eltype(data)}()
 
+    # All samples get the same value for the CPU profile.
+    value = [
+        1,      # events
+    ]
+
     idx = length(data)
-    value = nothing
     meta = nothing
     while idx > 0
-        if Profile.is_block_end(data, idx)
-            if value !== nothing
-                @assert meta !== nothing
+        if has_meta && Profile.is_block_end(data, idx)
+            if meta !== nothing
                 # Finish last block
                 push!(samples, Sample(;location_id = reverse!(location_id), value = value, label = meta))
                 location_id = Vector{eltype(data)}()
             end
 
-            # read metadata
+            # Consume all of the metadata entries in the buffer, and then position the IP
+            # at the idx for the actual ip.
             thread_sleeping = data[idx - Profile.META_OFFSET_SLEEPSTATE] - 1  # "Sleeping" is recorded as 1 or 2, to avoid 0s, which indicate end-of-block.
             cpu_cycle_clock = data[idx - Profile.META_OFFSET_CPUCYCLECLOCK]
             taskid = data[idx - Profile.META_OFFSET_TASKID]
             threadid = data[idx - Profile.META_OFFSET_THREADID]
 
-            value = [
-                1,                   # events
-            ]
             meta = Label[
                 Label!("thread_sleeping", thread_sleeping != 0),
                 Label!("cycle_clock", cpu_cycle_clock, "nanoseconds"),
@@ -176,6 +179,15 @@ function pprof(data::Union{Nothing, Vector{UInt}} = nothing,
             ]
             idx -= (Profile.nmeta + 2)  # skip all the metas, plus the 2 nulls that end a block.
             continue
+        elseif !has_meta && data[idx] == 0
+            # ip == 0x0 is the sentinel value for finishing a backtrace (when meta is disabled), therefore finising a sample
+            # On some platforms, we sometimes get two 0s in a row for some reason...
+            if idx > 1 && data[idx-1] == 0
+                idx -= 1
+            end
+            # Finish last block
+            push!(samples, Sample(;location_id = reverse!(location_id), value = value, label = meta))
+            location_id = Vector{eltype(data)}()
         end
         ip = data[idx]
         idx -= 1

test/PProf.jl

@@ -74,10 +74,14 @@ end
         end
         sleep(2)
     end
-    for i in 1:2
+    for i in 1:3
         if i == 1
             data = Profile.fetch(include_meta = true)
             args = (data,)
+        elseif i == 2
+            # Ensure we are backwards compatible with older, non-meta profiles
+            data = Profile.fetch(include_meta = false)
+            args = (data,)
         else
             data,lidict = Profile.retrieve(include_meta = true)
             args = (data, lidict)
@@ -94,9 +98,6 @@ end
         @test length(with_c.location) > length(without_c.location)
         @test length(with_c.var"#function") > length(without_c.var"#function")
     end
-
-    # Must have meta.
-    @test_throws AssertionError pprof(Profile.fetch(include_meta = false))
 end
 
 @testset "full_signatures" begin