From fb6a311de587ed3721538434d688524d2b2e2c95 Mon Sep 17 00:00:00 2001
From: Michael Karg <michael.karg@iohk.io>
Date: Tue, 21 Nov 2023 17:02:01 +0100
Subject: [PATCH] trace-resources: version 0.2.1.0; conditional compilation for
 netstat values

---
 trace-resources/CHANGELOG.md                  |  8 +++-
 .../src/Cardano/Logging/Resources/Linux.hs    | 43 ++++++++-----------
 trace-resources/trace-resources.cabal         |  9 ++++
 3 files changed, 33 insertions(+), 27 deletions(-)

diff --git a/trace-resources/CHANGELOG.md b/trace-resources/CHANGELOG.md
index 641629c3477..66a5b636a80 100644
--- a/trace-resources/CHANGELOG.md
+++ b/trace-resources/CHANGELOG.md
@@ -1,4 +1,10 @@
-# Revision history for trace-dispatcher
+# Revision history for trace-resources
+
+## 0.2.1.0 -- Nov 2023
+
+* Optimized resource record creation on Linux
+* Add microbenchmark for resource record creation
+* Add cabal flag `with-netstat` (default: False) to enable netstat values in Linux resource traces (potentially expensive)
 
 ## 0.2.0.2 -- Sep 2023
 
diff --git a/trace-resources/src/Cardano/Logging/Resources/Linux.hs b/trace-resources/src/Cardano/Logging/Resources/Linux.hs
index 0c02a9be047..7f560905150 100644
--- a/trace-resources/src/Cardano/Logging/Resources/Linux.hs
+++ b/trace-resources/src/Cardano/Logging/Resources/Linux.hs
@@ -8,9 +8,9 @@ module Cardano.Logging.Resources.Linux
 
 import           Cardano.Logging.Resources.Types
 import           Data.Maybe (fromMaybe)
-import           qualified Data.Text as T
-import           qualified Data.Text.IO as T (readFile)
-import           qualified Data.Text.Read as T (decimal)
+import qualified Data.Text as T
+import qualified Data.Text.IO as T (readFile)
+import qualified Data.Text.Read as T (decimal)
 import           Data.Word
 import qualified GHC.Stats as GhcStats
 import           System.Posix.Files (fileMode, getFileStatus, intersectFileModes, ownerReadMode)
@@ -84,30 +84,21 @@ readProcBlockInOut = do
 --   IpExt: 0 0 20053 8977 2437 23 3163525943 196480057 2426648 1491754 394285 5523 0 3513269 0 217426 0
 --
 readProcNetInOut :: IO (Word64, Word64)
+#ifdef WITH_NETSTAT
+readProcNetInOut = do
+  fields <- T.words . fourthLine . T.lines <$> T.readFile "/proc/self/net/netstat"
+  case -- We're only interested in 'InOctets' & 'OutOctets':
+    fmap readMaybeText . take 2 . drop 7 $ fields of
+      [Just netIn, Just netOut] -> pure (netIn, netOut)
+      _ -> pure (0, 0)
+  where
+    -- Assumption: 'IpExt:' values are on the fourth line of how the kernel displays the buffer
+    fourthLine ls = case drop 3 ls of
+      l:_ -> l
+      _   -> T.empty
+#else
 readProcNetInOut = pure (0, 0)
--- do
---     fields <- words . lastline . lines <$> readFile "/proc/self/net/netstat"
---     case -- We're only interested in 'InOctets' & 'OutOctets':
---       fmap readMaybe . take 2 . drop 7 $ fields of
---         [Just netIn, Just netOut] -> pure (netIn, netOut)
---         _ -> pure (0, 0)
---  where
---    lastline ls | length ls == 4 = last ls -- ensures we read the fourth line
---                | otherwise = []
-
--- readProcNetInOut = do
---     ipexts0 <- words <$> lastline <$> lines <$> readFile (pathProcNet pid)
---     let ipexts1 = map (\i -> readMaybe i :: Maybe Integer) ipexts0
---     return $
---       if length ipexts1 >= 9  -- enough fields available
---       then mkCounters [("IpExt:InOctets", ipexts1 !! 7), ("IpExt:OutOctets", ipexts1 !! 8)]
---       else []
---   where
---     lastline ls | length ls == 4 = last ls -- ensures we read the fourth line
---                 | otherwise = []
---     mkCounters = catMaybes . map (\(n,c) -> mkCounter n c)
---     mkCounter _n Nothing = Nothing
---     mkCounter n (Just i) = Just (Counter NetCounter (pack n) (Bytes $ fromInteger i))
+#endif
 
 -- | TODO we have to expand the |readMemStats| function
 -- to read full data from |proc|
diff --git a/trace-resources/trace-resources.cabal b/trace-resources/trace-resources.cabal
index fe3e6deac01..a1b35f2ce80 100644
--- a/trace-resources/trace-resources.cabal
+++ b/trace-resources/trace-resources.cabal
@@ -17,6 +17,11 @@ extra-source-files:     include/os-support-darwin.h
 extra-doc-files:        CHANGELOG.md
                         README.md
 
+Flag with-netstat
+    Description: Enable netstat values in Linux resource traces (potentially expensive)
+    Manual: True
+    Default: False
+
 common project-config
   default-language:     Haskell2010
 
@@ -28,6 +33,7 @@ library
                         Cardano.Logging.Resources.Dummy
 
   default-extensions:   OverloadedStrings
+                        CPP
   build-depends:        base >=4.12 && <5
                       , trace-dispatcher
                       , text
@@ -48,6 +54,9 @@ library
                         -Wmissing-export-lists
                         -Wno-incomplete-patterns
 
+  if flag(with-netstat)
+    CPP-options:        -DWITH_NETSTAT
+
   if os(linux)
     exposed-modules:    Cardano.Logging.Resources.Linux
   if os(windows)