From c1c4f74fc92219099af1ec419f543f961bea0720 Mon Sep 17 00:00:00 2001
From: Olly Betts <olly@survex.com>
Date: Sun, 22 Apr 2018 10:33:49 +1200
Subject: [PATCH] Track open fds in vector<bool> not set<int>

The lowest unused fd is used whenever a new fd is needed so we
can expect them to form a dense set and vector<bool> should be an
efficient representation both in space and time.
---
 xapian-core/tests/harness/fdtracker.cc | 30 ++++++++++++++++++++++++------
 xapian-core/tests/harness/fdtracker.h  | 14 ++++++++++++--
 2 files changed, 36 insertions(+), 8 deletions(-)

diff --git a/xapian-core/tests/harness/fdtracker.cc b/xapian-core/tests/harness/fdtracker.cc
index 22615117d..7fe08e038 100644
--- a/xapian-core/tests/harness/fdtracker.cc
+++ b/xapian-core/tests/harness/fdtracker.cc
@@ -49,6 +49,22 @@ using namespace std;
 # define FD_DIRECTORY "/dev/fd"
 #endif
 
+void
+FDTracker::mark_fd(int fd)
+{
+    if (fd >= 0) {
+	if (size_t(fd) >= fds.size())
+	    fds.resize((fd &~ 31) + 32);
+	fds[fd] = true;
+    }
+}
+
+bool
+FDTracker::check_fd(int fd) const
+{
+    return size_t(fd) < fds.size() && fds[fd];
+}
+
 FDTracker::~FDTracker()
 {
     if (dir_void) {
@@ -84,8 +100,7 @@ FDTracker::init()
 	if (name[0] < '0' || name[0] > '9')
 	    continue;
 
-	int fd = atoi(name);
-	fds.insert(fd);
+	mark_fd(atoi(name));
     }
 }
 
@@ -116,7 +131,10 @@ FDTracker::check()
 	    continue;
 
 	int fd = atoi(name);
-	if (fds.find(fd) != fds.end()) continue;
+	if (check_fd(fd)) {
+	    // This fd was already open before the testcase.
+	    continue;
+	}
 
 	string proc_symlink = FD_DIRECTORY "/";
 	proc_symlink += name;
@@ -129,7 +147,7 @@ FDTracker::check()
 	    memcmp(buf, "/dev/urandom", CONST_STRLEN("/dev/urandom")) == 0) {
 	    // /dev/urandom isn't a real leak - something in the C library
 	    // opens it lazily (at least on Linux).
-	    fds.insert(fd);
+	    mark_fd(fd);
 	    continue;
 	}
 
@@ -140,8 +158,8 @@ FDTracker::check()
 	    message.append(buf, res);
 	}
 
-	// Insert the leaked fd so we don't report it for future tests.
-	fds.insert(fd);
+	// Mark the leaked fd as used so we don't report it for future tests.
+	mark_fd(fd);
 	ok = false;
     }
     return ok;
diff --git a/xapian-core/tests/harness/fdtracker.h b/xapian-core/tests/harness/fdtracker.h
index bc8bd4639..32696b7ee 100644
--- a/xapian-core/tests/harness/fdtracker.h
+++ b/xapian-core/tests/harness/fdtracker.h
@@ -21,8 +21,8 @@
 #ifndef XAPIAN_INCLUDED_FDTRACKER_H
 #define XAPIAN_INCLUDED_FDTRACKER_H
 
-#include <set>
 #include <string>
+#include <vector>
 
 // Disable fd tracking where it can't possibly work.
 #ifndef __WIN32__
@@ -31,7 +31,13 @@
 
 class FDTracker {
 #ifdef XAPIAN_TESTSUITE_TRACK_FDS
-    std::set<int> fds;
+    /** Which fds are open.
+     *
+     *  The lowest unused fd is used whenever a new fd is needed so we
+     *  can expect them to form a dense set and vector<bool> should be an
+     *  efficient representation both in space and time.
+     */
+    std::vector<bool> fds;
 
     /** The DIR* from opendir("/proc/self/fd") (or equivalent) cast to void*.
      *
@@ -42,6 +48,10 @@ class FDTracker {
 
     std::string message;
 
+    void mark_fd(int fd);
+
+    bool check_fd(int fd) const;
+
   public:
     FDTracker() : dir_void(NULL) { }
 
-- 
2.11.4.GIT