core: add MemoryAvailable unit property

Try to infer the unused memory that a unit can claim before the
memory.max limit is reached, including any limit set on any parent
slice above the unit itself.

1 files changed, 25 insertions, 0 deletions

diff --git a/src/core/dbus-unit.c b/src/core/dbus-unit.c
index 6c04c6e5db..aa10939a04 100644
--- a/src/core/dbus-unit.c
+++ b/src/core/dbus-unit.c
@@ -1097,6 +1097,30 @@ static int property_get_current_memory(
         return sd_bus_message_append(reply, "t", sz);
 }
 
+static int property_get_available_memory(
+                sd_bus *bus,
+                const char *path,
+                const char *interface,
+                const char *property,
+                sd_bus_message *reply,
+                void *userdata,
+                sd_bus_error *error) {
+
+        uint64_t sz = UINT64_MAX;
+        Unit *u = userdata;
+        int r;
+
+        assert(bus);
+        assert(reply);
+        assert(u);
+
+        r = unit_get_memory_available(u, &sz);
+        if (r < 0 && r != -ENODATA)
+                log_unit_warning_errno(u, r, "Failed to get total available memory from cgroup: %m");
+
+        return sd_bus_message_append(reply, "t", sz);
+}
+
 static int property_get_current_tasks(
                 sd_bus *bus,
                 const char *path,
@@ -1541,6 +1565,7 @@ const sd_bus_vtable bus_unit_cgroup_vtable[] = {
         SD_BUS_PROPERTY("Slice", "s", property_get_slice, 0, 0),
         SD_BUS_PROPERTY("ControlGroup", "s", property_get_cgroup, 0, 0),
         SD_BUS_PROPERTY("MemoryCurrent", "t", property_get_current_memory, 0, 0),
+        SD_BUS_PROPERTY("MemoryAvailable", "t", property_get_available_memory, 0, 0),
         SD_BUS_PROPERTY("CPUUsageNSec", "t", property_get_cpu_usage, 0, 0),
         SD_BUS_PROPERTY("EffectiveCPUs", "ay", property_get_cpuset_cpus, 0, 0),
         SD_BUS_PROPERTY("EffectiveMemoryNodes", "ay", property_get_cpuset_mems, 0, 0),