Make max_discrepancies_before_demotion configurable via DISTCC_MAX_DISCREPANCY environment variable.

4 files changed, 46 insertions, 7 deletions

diff --git a/man/distcc.1 b/man/distcc.1
index 283f868..e3528cb 100644
--- a/man/distcc.1
+++ b/man/distcc.1
@@ -800,6 +800,10 @@ locally.  Built-in heuristics prevent some such discrepancy email from being sen
 the problem is that a local file changed between the failing remote compilation
 and the succeeding local compilation.
 .TP
+.B "DISTCC_MAX_DISCREPANCY"
+The maximum number of remote compilation failures allowed in pump mode before
+distcc switches to plain distcc mode. By default set to 1.
+.TP
 .B "DCC_EMAILLOG_WHOM_TO_BLAME"
 The email address for discrepancy email; the default is "distcc-pump-errors".
 .TP
diff --git a/man/pump.1 b/man/pump.1
index 11da428..5177c2d 100644
--- a/man/pump.1
+++ b/man/pump.1
@@ -127,6 +127,11 @@ pump script in the installation executes), then
 Python executables and distcc itself will be retrieved
 from the parent directory of the location.
 .TP
+.B "DISTCC_MAX_DISCREPANCY"
+see the
+.BR distcc(1)
+man page.
+.TP
 .B DISTCC_POTENTIAL_HOSTS
 The distcc servers that will be queried by lsdistcc
 in order to produce a value for DISTCC_HOSTS.
diff --git a/pump.in b/pump.in
index 9597096..acad32c 100755
--- a/pump.in
+++ b/pump.in
@@ -139,9 +139,19 @@ GetScriptDir() {
 
 # Constants used by this process.
 
-# TODO(klarlund) This value must be the same as that in src/compile.c. See
+# The default value must be the same as that in src/compile.c. See
 # comment there.
 max_discrepancies_before_demotion=1
+if [ -n "$DISTCC_MAX_DISCREPANCY" ] ; then
+  if [ "$DISTCC_MAX_DISCREPANCY" -le 0 ] ; then
+    echo "$0:" \
+            "Bad DISTCC_MAX_DISCREPANCY value: \"$DISTCC_MAX_DISCREPANCY\"." \
+            "Needs to be 1 or greater." \
+            1>&2
+    exit 1
+  fi
+  max_discrepancies_before_demotion="$DISTCC_MAX_DISCREPANCY"
+fi
 
 
 # Variables inherited from the environment of the caller.
diff --git a/src/compile.c b/src/compile.c
index 2fc60b7..edd605d 100644
--- a/src/compile.c
+++ b/src/compile.c
@@ -68,13 +68,33 @@
  */
 int dcc_scan_includes = 0;
 
-/* TODO(klarlund)Warning: this constant should have the same value as in the
- * pump.in script! Make it configurable and user changeable.*/
-static const int max_discrepancies_before_demotion = 1;
-
 static const char *const include_server_port_suffix = "/socket";
 static const char *const discrepancy_suffix = "/discrepancy_counter";
 
+static int dcc_get_max_discrepancies_before_demotion(void)
+{
+    /* Warning: the default setting here should have the same value as in the
+     * pump.in script! */
+    static const int default_setting = 1;
+    static int current_setting = 0;
+
+    if (current_setting > 0)
+        return current_setting;
+
+    const char *user_setting = getenv("DISTCC_MAX_DISCREPANCY");
+    if (user_setting) {
+        int parsed_user_setting = atoi(user_setting);
+        if (parsed_user_setting <= 0) {
+            rs_log_error("Bad DISTCC_MAX_DISCREPANCY value: %s", user_setting);
+            exit(EXIT_BAD_ARGUMENTS);
+        }
+        current_setting = parsed_user_setting;
+    } else {
+        current_setting = default_setting;
+    }
+    return current_setting;
+}
+
 /**
  * Return in @param filename the name of the file we use as unary counter of
  * discrepancies (a compilation failing on the server, but succeeding
@@ -158,7 +178,7 @@ static int dcc_note_discrepancy(const char *discrepancy_filename)
     assured that exactly one process will take the 'if' branch when
     max_discrepancies_before_demotion failures is reached. */
     if (ftell(discrepancy_file) == 
-        (long int)max_discrepancies_before_demotion) {
+        (long int)dcc_get_max_discrepancies_before_demotion()) {
         rs_log_warning("now using plain distcc, possibly due to "
                        "inconsistent file system changes during build");
     }
@@ -182,7 +202,7 @@ static void dcc_perhaps_adjust_cpp_where_and_protover(
     /* Check whether there has been too much trouble running distcc-pump during
        this build. */
     if (dcc_read_number_discrepancies(discrepancy_filename) >=
-        max_discrepancies_before_demotion) {
+        dcc_get_max_discrepancies_before_demotion()) {
         /* Give up on using distcc-pump */
         host->cpp_where = DCC_CPP_ON_CLIENT;
         dcc_get_protover_from_features(host->compr,