params: move blocking read to Cython and remove C++ signal handling

common/params.cc

@@ -5,7 +5,6 @@
 
 #include <algorithm>
 #include <cassert>
-#include <csignal>
 #include <unordered_map>
 
 #include "common/queue.h"
@@ -15,11 +14,6 @@
 
 namespace {
 
-volatile sig_atomic_t params_do_exit = 0;
-void params_sig_handler(int signal) {
-  params_do_exit = 1;
-}
-
 int fsync_dir(const std::string &path) {
   int result = -1;
   int fd = HANDLE_EINTR(open(path.c_str(), O_RDONLY, 0755));
@@ -282,27 +276,8 @@ int Params::remove(const std::string &key) {
   return fsync_dir(getParamPath());
 }
 
-std::string Params::get(const std::string &key, bool block) {
-  if (!block) {
-    return util::read_file(getParamPath(key));
-  } else {
-    // blocking read until successful
-    params_do_exit = 0;
-    void (*prev_handler_sigint)(int) = std::signal(SIGINT, params_sig_handler);
-    void (*prev_handler_sigterm)(int) = std::signal(SIGTERM, params_sig_handler);
-
-    std::string value;
-    while (!params_do_exit) {
-      if (value = util::read_file(getParamPath(key)); !value.empty()) {
-        break;
-      }
-      util::sleep_for(100);  // 0.1 s
-    }
-
-    std::signal(SIGINT, prev_handler_sigint);
-    std::signal(SIGTERM, prev_handler_sigterm);
-    return value;
-  }
+std::string Params::get(const std::string &key) {
+  return util::read_file(getParamPath(key));
 }
 
 std::map<std::string, std::string> Params::readAll() {

common/params.h

@@ -39,9 +39,9 @@ class Params {
   void clearAll(ParamKeyType type);
 
   // helpers for reading values
-  std::string get(const std::string &key, bool block = false);
-  inline bool getBool(const std::string &key, bool block = false) {
-    return get(key, block) == "1";
+  std::string get(const std::string &key);
+  inline bool getBool(const std::string &key) {
+    return get(key) == "1";
   }
   std::map<std::string, std::string> readAll();
 

common/params_pyx.pyx

@@ -1,5 +1,6 @@
 # distutils: language = c++
 # cython: language_level = 3
+import time
 from libcpp cimport bool
 from libcpp.string cimport string
 from libcpp.vector cimport vector
@@ -15,8 +16,8 @@ cdef extern from "common/params.h":
 
   cdef cppclass c_Params "Params":
     c_Params(string) except + nogil
-    string get(string, bool) nogil
-    bool getBool(string, bool) nogil
+    string get(string) nogil
+    bool getBool(string) nogil
     int remove(string) nogil
     int put(string, string) nogil
     void putNonBlocking(string, string) nogil
@@ -63,24 +64,22 @@ cdef class Params:
     cdef string k = self.check_key(key)
     cdef string val
     with nogil:
-      val = self.p.get(k, block)
+      val = self.p.get(k)
 
-    if val == b"":
-      if block:
-        # If we got no value while running in blocked mode
-        # it means we got an interrupt while waiting
-        raise KeyboardInterrupt
-      else:
-        return None
+    # If blocking is enabled, loop until a non-empty value is retrieved
+    while block and val == b"":
+      time.sleep(0.1)
+      with nogil:
+        val = self.p.get(k)
 
+    if val == b"":
+      return None
     return val if encoding is None else val.decode(encoding)
 
   def get_bool(self, key, bool block=False):
     cdef string k = self.check_key(key)
-    cdef bool r
-    with nogil:
-      r = self.p.getBool(k, block)
-    return r
+    val = self.get(k, block)
+    return True if val == b"1" else False
 
   def put(self, key, dat):
     """