library: <STAT> api, change for that 'get' return type

The following commit message is shared with 4 patches.
------------------------------------------------------

Under the newlib interface most of our 'get' functions
represent a bit of a compromise in that the actual raw
values are coerced into one (probably ok) return type.

That approach creates the possibility of truncation at
best, and wouldn't serve future needs should something
other than numeric data be added to the 'get' results.

This commit trades the current compromise for a return
value guaranteed to satisfy all future needs, namely a
pointer to a particular api's specific results struct.

The impact on existing programs is minimal, especially
when using a new supplied macro. Otherwise, native 'C'
syntax could be used, but may feel somewhat unnatural.

[ as an aside, this new approach allows us to delete ]
[ all 'getsfunc' table entries & the supporting code ]

Signed-off-by: Jim Warner <james.warner@comcast.net>

diff --git a/proc/stat.c b/proc/stat.c
index e39ef30db2caac5cfcefdff5e36c7da7cf27f2d7..3c174613b12a99f4dffe02fd825ca28971b765f3 100644 (file)
--- a/proc/stat.c
+++ b/proc/stat.c
@@ -122,6 +122,7 @@ struct procps_statinfo {
     int (*our_max_node)(void);         // a libnuma function call via dlsym()
     int (*our_node_of_cpu)(int);       // a libnuma function call via dlsym()
 #endif
+    struct stat_result get_this;       // for return to caller after a get
 };
 
 
@@ -192,129 +193,60 @@ setDECL(SYS_DELTA_PROC_RUNNING) { (void)T; R->result.s_int = S->new.procs_runnin
 #undef SYSsetH
 
 
-// ___ Results 'Get' Support ||||||||||||||||||||||||||||||||||||||||||||||||||
-
-#define getNAME(e) get_results_ ## e
-#define getDECL(e) static signed long getNAME(e) \
-    (struct procps_statinfo *I)
-
-// regular get
-#define TIC_get(e,x) getDECL(e) { return I->cpu_hist.new . x; }
-#define SYS_get(e,x) getDECL(e) { return I->sys_hist.new . x; }
-// delta get
-#define TICgetH(e,x) getDECL(e) { \
-    long long n = I->cpu_hist.new. x - I->cpu_hist.old. x; \
-    return n < 0 ? 0 : n; }
-#define SYSgetH(e,x) getDECL(e) { \
-    long long n = I->sys_hist.new. x - I->sys_hist.old. x; \
-    return n < 0 ? 0 : n; }
-
-getDECL(noop)                   { (void)I; return 0; }
-getDECL(extra)                  { (void)I; return 0; }
-
-getDECL(TIC_ID)                 { return I->cpu_hist.id;  }
-getDECL(TIC_NUMA_NODE)          { return I->cpu_hist.numa_node; }
-
-TIC_get(TIC_USER,                 user)
-TIC_get(TIC_NICE,                 nice)
-TIC_get(TIC_SYSTEM,               system)
-TIC_get(TIC_IDLE,                 idle)
-TIC_get(TIC_IOWAIT,               iowait)
-TIC_get(TIC_IRQ,                  irq)
-TIC_get(TIC_SOFTIRQ,              sirq)
-TIC_get(TIC_STOLEN,               stolen)
-TIC_get(TIC_GUEST,                guest)
-TIC_get(TIC_GUEST_NICE,           gnice)
-
-TICgetH(TIC_DELTA_USER,           user)
-TICgetH(TIC_DELTA_NICE,           nice)
-TICgetH(TIC_DELTA_SYSTEM,         system)
-TICgetH(TIC_DELTA_IDLE,           idle)
-TICgetH(TIC_DELTA_IOWAIT,         iowait)
-TICgetH(TIC_DELTA_IRQ,            irq)
-TICgetH(TIC_DELTA_SOFTIRQ,        sirq)
-TICgetH(TIC_DELTA_STOLEN,         stolen)
-TICgetH(TIC_DELTA_GUEST,          guest)
-TICgetH(TIC_DELTA_GUEST_NICE,     gnice)
-
-SYS_get(SYS_CTX_SWITCHES,         ctxt)
-SYS_get(SYS_INTERRUPTS,           intr)
-SYS_get(SYS_PROC_BLOCKED,         procs_blocked)
-SYS_get(SYS_PROC_CREATED,         procs_created)
-SYS_get(SYS_PROC_RUNNING,         procs_running)
-SYS_get(SYS_TIME_OF_BOOT,         btime)
-
-SYSgetH(SYS_DELTA_CTX_SWITCHES,   ctxt)
-SYSgetH(SYS_DELTA_INTERRUPTS,     intr)
-getDECL(SYS_DELTA_PROC_BLOCKED) { return I->sys_hist.new.procs_blocked - I->sys_hist.old.procs_blocked; }
-SYSgetH(SYS_DELTA_PROC_CREATED,  procs_created)
-getDECL(SYS_DELTA_PROC_RUNNING) { return I->sys_hist.new.procs_running - I->sys_hist.old.procs_running; }
-
-#undef getDECL
-#undef TIC_get
-#undef SYS_get
-#undef TICgetH
-#undef SYSgetH
-
-
 // ___ Controlling Table ||||||||||||||||||||||||||||||||||||||||||||||||||||||
 
 typedef void (*SET_t)(struct stat_result *, struct hist_sys *, struct hist_tic *);
 #define RS(e) (SET_t)setNAME(e)
 
-typedef long long (*GET_t)(struct procps_statinfo *);
-#define RG(e) (GET_t)getNAME(e)
-
         /*
          * Need it be said?
          * This table must be kept in the exact same order as
          * those 'enum stat_item' guys ! */
 static struct {
     SET_t setsfunc;              // the actual result setting routine
-    GET_t getsfunc;              // a routine to return single result
 } Item_table[] = {
-/*  setsfunc                     getsfunc
-    ---------------------------  -------------------------  */
-  { RS(noop),                    RG(noop)                   },
-  { RS(extra),                   RG(extra)                  },
-
-  { RS(TIC_ID),                  RG(TIC_ID)                 },
-  { RS(TIC_NUMA_NODE),           RG(TIC_NUMA_NODE)          },
-  { RS(TIC_USER),                RG(TIC_USER)               },
-  { RS(TIC_NICE),                RG(TIC_NICE)               },
-  { RS(TIC_SYSTEM),              RG(TIC_SYSTEM)             },
-  { RS(TIC_IDLE),                RG(TIC_IDLE)               },
-  { RS(TIC_IOWAIT),              RG(TIC_IOWAIT)             },
-  { RS(TIC_IRQ),                 RG(TIC_IRQ)                },
-  { RS(TIC_SOFTIRQ),             RG(TIC_SOFTIRQ)            },
-  { RS(TIC_STOLEN),              RG(TIC_STOLEN)             },
-  { RS(TIC_GUEST),               RG(TIC_GUEST)              },
-  { RS(TIC_GUEST_NICE),          RG(TIC_GUEST_NICE)         },
-  { RS(TIC_DELTA_USER),          RG(TIC_DELTA_USER)         },
-  { RS(TIC_DELTA_NICE),          RG(TIC_DELTA_NICE)         },
-  { RS(TIC_DELTA_SYSTEM),        RG(TIC_DELTA_SYSTEM)       },
-  { RS(TIC_DELTA_IDLE),          RG(TIC_DELTA_IDLE)         },
-  { RS(TIC_DELTA_IOWAIT),        RG(TIC_DELTA_IOWAIT)       },
-  { RS(TIC_DELTA_IRQ),           RG(TIC_DELTA_IRQ)          },
-  { RS(TIC_DELTA_SOFTIRQ),       RG(TIC_DELTA_SOFTIRQ)      },
-  { RS(TIC_DELTA_STOLEN),        RG(TIC_DELTA_STOLEN)       },
-  { RS(TIC_DELTA_GUEST),         RG(TIC_DELTA_GUEST)        },
-  { RS(TIC_DELTA_GUEST_NICE),    RG(TIC_DELTA_GUEST_NICE)   },
-
-  { RS(SYS_CTX_SWITCHES),        RG(SYS_CTX_SWITCHES)       },
-  { RS(SYS_INTERRUPTS),          RG(SYS_INTERRUPTS)         },
-  { RS(SYS_PROC_BLOCKED),        RG(SYS_PROC_BLOCKED)       },
-  { RS(SYS_PROC_CREATED),        RG(SYS_PROC_CREATED)       },
-  { RS(SYS_PROC_RUNNING),        RG(SYS_PROC_RUNNING)       },
-  { RS(SYS_TIME_OF_BOOT),        RG(SYS_TIME_OF_BOOT)       },
-  { RS(SYS_DELTA_CTX_SWITCHES),  RG(SYS_DELTA_CTX_SWITCHES) },
-  { RS(SYS_DELTA_INTERRUPTS),    RG(SYS_DELTA_INTERRUPTS)   },
-  { RS(SYS_DELTA_PROC_BLOCKED),  RG(SYS_DELTA_PROC_BLOCKED) },
-  { RS(SYS_DELTA_PROC_CREATED),  RG(SYS_DELTA_PROC_CREATED) },
-  { RS(SYS_DELTA_PROC_RUNNING),  RG(SYS_DELTA_PROC_RUNNING) },
+/*  setsfunc
+    -------------------------- */
+  { RS(noop)                   },
+  { RS(extra)                  },
+
+  { RS(TIC_ID)                 },
+  { RS(TIC_NUMA_NODE)          },
+  { RS(TIC_USER)               },
+  { RS(TIC_NICE)               },
+  { RS(TIC_SYSTEM)             },
+  { RS(TIC_IDLE)               },
+  { RS(TIC_IOWAIT)             },
+  { RS(TIC_IRQ)                },
+  { RS(TIC_SOFTIRQ)            },
+  { RS(TIC_STOLEN)             },
+  { RS(TIC_GUEST)              },
+  { RS(TIC_GUEST_NICE)         },
+  { RS(TIC_DELTA_USER)         },
+  { RS(TIC_DELTA_NICE)         },
+  { RS(TIC_DELTA_SYSTEM)       },
+  { RS(TIC_DELTA_IDLE)         },
+  { RS(TIC_DELTA_IOWAIT)       },
+  { RS(TIC_DELTA_IRQ)          },
+  { RS(TIC_DELTA_SOFTIRQ)      },
+  { RS(TIC_DELTA_STOLEN)       },
+  { RS(TIC_DELTA_GUEST)        },
+  { RS(TIC_DELTA_GUEST_NICE)   },
+
+  { RS(SYS_CTX_SWITCHES)       },
+  { RS(SYS_INTERRUPTS)         },
+  { RS(SYS_PROC_BLOCKED)       },
+  { RS(SYS_PROC_CREATED)       },
+  { RS(SYS_PROC_RUNNING)       },
+  { RS(SYS_TIME_OF_BOOT)       },
+  { RS(SYS_DELTA_CTX_SWITCHES) },
+  { RS(SYS_DELTA_INTERRUPTS)   },
+  { RS(SYS_DELTA_PROC_BLOCKED) },
+  { RS(SYS_DELTA_PROC_CREATED) },
+  { RS(SYS_DELTA_PROC_RUNNING) },
 
  // dummy entry corresponding to PROCPS_STAT_logical_end ...
-  { NULL,                        NULL                       }
+  { NULL,                      }
 };
 
     /* please note,
@@ -326,9 +258,7 @@ enum stat_item PROCPS_STAT_TIC_highest = PROCPS_STAT_TIC_DELTA_GUEST_NICE;
 enum stat_item PROCPS_STAT_logical_end = PROCPS_STAT_SYS_DELTA_PROC_RUNNING + 1;
 
 #undef setNAME
-#undef getNAME
 #undef RS
-#undef RG
 
 // ___ Private Functions ||||||||||||||||||||||||||||||||||||||||||||||||||||||
 
@@ -930,29 +860,34 @@ PROCPS_EXPORT int procps_stat_unref (
 
 // --- variable interface functions -------------------------------------------
 
-PROCPS_EXPORT signed long long procps_stat_get (
+PROCPS_EXPORT struct stat_result *procps_stat_get (
         struct procps_statinfo *info,
         enum stat_item item)
 {
     static time_t sav_secs;
     time_t cur_secs;
-    int rc;
 
     if (info == NULL)
-        return -EINVAL;
+        return NULL;
     if (item < 0 || item >= PROCPS_STAT_logical_end)
-        return -EINVAL;
+        return NULL;
 
     /* no sense reading the stat with every call from a program like vmstat
        who chooses not to use the much more efficient 'select' function ... */
     cur_secs = time(NULL);
     if (1 <= cur_secs - sav_secs) {
-        if ((rc = read_stat_failed(info)))
-            return rc;
+        if (read_stat_failed(info))
+            return NULL;
         sav_secs = cur_secs;
     }
 
-    return Item_table[item].getsfunc(info);
+    info->get_this.item = item;
+//  with 'get', we must NOT honor the usual 'noop' guarantee
+//  if (item > PROCPS_STAT_noop)
+        info->get_this.result.ull_int = 0;
+    Item_table[item].setsfunc(&info->get_this, &info->sys_hist, &info->cpu_hist);
+
+    return &info->get_this;
 } // end: procps_stat_get
 
 

diff --git a/proc/stat.h b/proc/stat.h
index 1ebf7949302b184fa45d42cf0da8dd2a2db1606e..6642ad708401548cc5f73fb0d3ed07591e95fdf5 100644 (file)
--- a/proc/stat.h
+++ b/proc/stat.h
@@ -97,8 +97,11 @@ struct stat_reaped {
 #define PROCPS_STAT_SUMMARY_ID    -11111
 #define PROCPS_STAT_NODE_INVALID  -22222
 
-#define PROCPS_STAT_VAL(rel_enum,type,stack) \
-    stack -> head [ rel_enum ] . result . type
+#define PROCPS_STAT_GET( statinfo, actual_enum, type ) \
+    procps_stat_get( statinfo, actual_enum ) -> result . type
+
+#define PROCPS_STAT_VAL( relative_enum, type, stack ) \
+    stack -> head [ relative_enum ] . result . type
 
 
 struct procps_statinfo;
@@ -107,7 +110,7 @@ int procps_stat_new   (struct procps_statinfo **info);
 int procps_stat_ref   (struct procps_statinfo  *info);
 int procps_stat_unref (struct procps_statinfo **info);
 
-signed long long procps_stat_get (
+struct stat_result *procps_stat_get (
     struct procps_statinfo *info,
     enum stat_item item);