Minor fixes to safe_byte_ranges, but will need to wait to tonight with a proper POSIX machine to debug.

3 files changed, 20 insertions, 13 deletions

diff --git a/include/afio/v2.0/detail/impl/posix/utils.ipp b/include/afio/v2.0/detail/impl/posix/utils.ipp
index c6c37ec0..e2bd0bf9 100644
--- a/include/afio/v2.0/detail/impl/posix/utils.ipp
+++ b/include/afio/v2.0/detail/impl/posix/utils.ipp
@@ -117,13 +117,14 @@ namespace utils
   void random_fill(char *buffer, size_t bytes) noexcept
   {
     static QUICKCPPLIB_NAMESPACE::configurable_spinlock::spinlock<bool> lock;
-    static int randomfd = -1;
-    if(-1 == randomfd)
+    static std::atomic<int> randomfd(-1);
+    int fd = randomfd;
+    if(-1 == fd)
     {
       std::lock_guard<decltype(lock)> g(lock);
-      randomfd = ::open("/dev/urandom", O_RDONLY);
+      randomfd = fd = ::open("/dev/urandom", O_RDONLY);
     }
-    if(-1 == randomfd || ::read(randomfd, buffer, bytes) < (ssize_t) bytes)
+    if(-1 == fd || ::read(fd, buffer, bytes) < (ssize_t) bytes)
     {
       AFIO_LOG_FATAL(0, "afio: Kernel crypto function failed");
       std::terminate();
diff --git a/include/afio/v2.0/detail/impl/safe_byte_ranges.ipp b/include/afio/v2.0/detail/impl/safe_byte_ranges.ipp
index 162bb328..aea2db85 100644
--- a/include/afio/v2.0/detail/impl/safe_byte_ranges.ipp
+++ b/include/afio/v2.0/detail/impl/safe_byte_ranges.ipp
@@ -86,6 +86,8 @@ namespace algorithm
         void _unlock(unsigned mythreadid, entity_type entity)
         {
           auto it = _thread_locks.find(entity.value);
+          assert(it != _thread_locks.end());
+          assert(it->second.writer_tid == mythreadid || it->second.writer_tid == 0);
           if(it->second.writer_tid == mythreadid)
           {
             if(!it->second.reader_tids.empty())
@@ -101,14 +103,17 @@ namespace algorithm
               return;
             }
           }
-          // Remove me from reader tids
-          auto reader_tid_it = std::find(it->second.reader_tids.begin(), it->second.reader_tids.end(), mythreadid);
-          assert(reader_tid_it != it->second.reader_tids.end());
-          if(reader_tid_it != it->second.reader_tids.end())
+          else
           {
-            // We don't care about the order, so fastest is to swap this tid with final tid and resize down
-            std::swap(*reader_tid_it, it->second.reader_tids.back());
-            it->second.reader_tids.pop_back();
+            // Remove me from reader tids
+            auto reader_tid_it = std::find(it->second.reader_tids.begin(), it->second.reader_tids.end(), mythreadid);
+            assert(reader_tid_it != it->second.reader_tids.end());
+            if(reader_tid_it != it->second.reader_tids.end())
+            {
+              // We don't care about the order, so fastest is to swap this tid with final tid and resize down
+              std::swap(*reader_tid_it, it->second.reader_tids.back());
+              it->second.reader_tids.pop_back();
+            }
           }
           if(it->second.reader_tids.empty())
           {
diff --git a/release_notes.md b/release_notes.md
index 80978374..81538af1 100644
--- a/release_notes.md
+++ b/release_notes.md
@@ -35,7 +35,7 @@ Manufacturer claimed 4Kb transfer latencies for the physical hardware:
 - &lt; 99% SATA flash drive latency: Windows **290us** Linux **158us**
 - &lt; 99% NVMe drive latency: Windows **150us** FreeBSD **70us** Linux **30us**
 
-Lowest achievable 4Kb read latency benchmarked to date by author: **0.19us** (5.3M IOPS @ QD1, approx 20Gb/sec)
+Empirical AFIO read latency benchmarked by author: **0.19us** (5.3M IOPS @ QD1, approx 20Gb/sec)
 </td>
 <td valign="top" width="33%">
 75% read 25% write QD4 4Kb direct transfer latencies for the software with AFIO:
@@ -43,7 +43,7 @@ Lowest achievable 4Kb read latency benchmarked to date by author: **0.19us** (5.
 - &lt; 99% SATA flash drive latency: Windows **1,812us** Linux **1,416us**
 - &lt; 99% NVMe drive latency: Windows **95us** FreeBSD **143us** Linux **40us**
 
-Lowest achievable 4Kb write latency benchmarked to date by author: **0.18us** (5.6M IOPS @ QD1, approx 21Gb/sec)
+Empirical AFIO write latency benchmarked by author: **0.18us** (5.6M IOPS @ QD1, approx 21Gb/sec)
 </td>
 </tr>
 </table>
@@ -142,6 +142,7 @@ Todo:
 | ✔ | ✔ | ✔ | Universal portable UTF-8 path views.
 |   | ✔ | ✔ | "Hole punching" and hole enumeration ported over from AFIO v1.
 |   | ✔ | ✔ | Directory handles and very fast directory enumeration ported over from AFIO v1.
+| ✔ | ✔ | ✔ | `shared_fs_mutex` shared/exclusive entities locking based on safe byte ranges
 
 Todo to reach feature parity with AFIO v1: