library: <SLABINFO> api, change 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/slabinfo.c b/proc/slabinfo.c
index 8249cc0331e40d295231825a19b350eab2b3bd32..75b8df1014e7113e3d3a82a112e1824be175505f 100644 (file)
--- a/proc/slabinfo.c
+++ b/proc/slabinfo.c
@@ -120,14 +120,15 @@ struct procps_slabinfo {
     int refcount;
     FILE *slabinfo_fp;
     int slabinfo_was_read;
-    int nodes_alloc;                /* nodes alloc()ed */
-    int nodes_used;                 /* nodes using alloced memory */
-    struct slabs_node *nodes;       /* first slabnode of this list */
-    struct slabs_hist hist;         /* new/old slabs_summ data */
-    struct ext_support select_ext;  /* supports concurrent select/reap */
-    struct ext_support fetch_ext;   /* supports concurrent select/reap */
-    struct fetch_support fetch;     /* support for procps_slabinfo_reap */
-    struct slabs_node nul_node;     /* used by procps_slabinfo_select */
+    int nodes_alloc;                   /* nodes alloc()ed */
+    int nodes_used;                    /* nodes using alloced memory */
+    struct slabs_node *nodes;          /* first slabnode of this list */
+    struct slabs_hist hist;            /* new/old slabs_summ data */
+    struct ext_support select_ext;     /* supports concurrent select/reap */
+    struct ext_support fetch_ext;      /* supports concurrent select/reap */
+    struct fetch_support fetch;        /* support for procps_slabinfo_reap */
+    struct slabs_node nul_node;        /* used by slabinfo_get/select */
+    struct slabinfo_result get_this;   /* used by slabinfo_get */
 };
 
 
@@ -189,65 +190,6 @@ NOD_set(SLABNODE_SIZE,           ul_int,  cache_size)
 #undef HST_set
 
 
-// ___ Results 'Get' Support ||||||||||||||||||||||||||||||||||||||||||||||||||
-
-#define getNAME(e) get_results_ ## e
-#define getDECL(e) static signed long getNAME(e) \
-    (struct procps_slabinfo *I)
-
-// regular get
-#define REG_get(e,t,x) getDECL(e) { return I->hist.new. x; }
-// delta get
-#define HST_get(e,t,x) getDECL(e) { return (signed long)I->hist.new. x - I->hist.old. x; }
-// illogical get
-#define NOT_get(e) getDECL(e)     { (void)I; return 0; }
-
-NOT_get(noop)
-NOT_get(extra)
-
-REG_get(SLABS_OBJS,               u_int,  nr_objs)
-REG_get(SLABS_AOBJS,              u_int,  nr_active_objs)
-REG_get(SLABS_PAGES,              u_int,  nr_pages)
-REG_get(SLABS_SLABS,              u_int,  nr_slabs)
-REG_get(SLABS_ASLABS,             u_int,  nr_active_slabs)
-REG_get(SLABS_CACHES,             u_int,  nr_caches)
-REG_get(SLABS_ACACHES,            u_int,  nr_active_caches)
-REG_get(SLABS_SIZE_AVG,           u_int,  avg_obj_size)
-REG_get(SLABS_SIZE_MIN,           u_int,  min_obj_size)
-REG_get(SLABS_SIZE_MAX,           u_int,  max_obj_size)
-REG_get(SLABS_SIZE_ACTIVE,       ul_int,  active_size)
-REG_get(SLABS_SIZE_TOTAL,        ul_int,  total_size)
-
-HST_get(SLABS_DELTA_OBJS,         s_int,  nr_objs)
-HST_get(SLABS_DELTA_AOBJS,        s_int,  nr_active_objs)
-HST_get(SLABS_DELTA_PAGES,        s_int,  nr_pages)
-HST_get(SLABS_DELTA_SLABS,        s_int,  nr_slabs)
-HST_get(SLABS_DELTA_ASLABS,       s_int,  nr_active_slabs)
-HST_get(SLABS_DELTA_CACHES,       s_int,  nr_caches)
-HST_get(SLABS_DELTA_ACACHES,      s_int,  nr_active_caches)
-HST_get(SLABS_DELTA_SIZE_AVG,     s_int,  avg_obj_size)
-HST_get(SLABS_DELTA_SIZE_MIN,     s_int,  min_obj_size)
-HST_get(SLABS_DELTA_SIZE_MAX,     s_int,  max_obj_size)
-HST_get(SLABS_DELTA_SIZE_ACTIVE,  s_int,  active_size)
-HST_get(SLABS_DELTA_SIZE_TOTAL,   s_int,  total_size)
-
-NOT_get(SLABNODE_NAME)
-NOT_get(SLABNODE_OBJS)
-NOT_get(SLABNODE_AOBJS)
-NOT_get(SLABNODE_OBJ_SIZE)
-NOT_get(SLABNODE_OBJS_PER_SLAB)
-NOT_get(SLABNODE_PAGES_PER_SLAB)
-NOT_get(SLABNODE_SLABS)
-NOT_get(SLABNODE_ASLABS)
-NOT_get(SLABNODE_USE)
-NOT_get(SLABNODE_SIZE)
-
-#undef getDECL
-#undef REG_get
-#undef HST_get
-#undef NOT_get
-
-
 // ___ Sorting Support ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
 
 struct sort_parms {
@@ -294,9 +236,6 @@ srtDECL(noop) { \
 typedef void (*SET_t)(struct slabinfo_result *, struct slabs_hist *, struct slabs_node *);
 #define RS(e) (SET_t)setNAME(e)
 
-typedef signed long (*GET_t)(struct procps_slabinfo *);
-#define RG(e) (GET_t)getNAME(e)
-
 typedef int  (*QSR_t)(const void *, const void *, void *);
 #define QS(t) (QSR_t)srtNAME(t)
 
@@ -306,53 +245,52 @@ typedef int  (*QSR_t)(const void *, const void *, void *);
          * those *enum slabinfo_item* guys ! */
 static struct {
     SET_t setsfunc;              // the actual result setting routine
-    GET_t getsfunc;              // a routine to return single result
     QSR_t sortfunc;              // sort cmp func for a specific type
 } Item_table[] = {
-/*  setsfunc                     getsfunc                     sortfunc
-    ---------------------------  ---------------------------  ---------  */
-  { RS(noop),                    RG(noop),                    QS(ul_int) },
-  { RS(extra),                   RG(extra),                   QS(noop)   },
-
-  { RS(SLABS_OBJS),              RG(SLABS_OBJS),              QS(noop)   },
-  { RS(SLABS_AOBJS),             RG(SLABS_AOBJS),             QS(noop)   },
-  { RS(SLABS_PAGES),             RG(SLABS_PAGES),             QS(noop)   },
-  { RS(SLABS_SLABS),             RG(SLABS_SLABS),             QS(noop)   },
-  { RS(SLABS_ASLABS),            RG(SLABS_ASLABS),            QS(noop)   },
-  { RS(SLABS_CACHES),            RG(SLABS_CACHES),            QS(noop)   },
-  { RS(SLABS_ACACHES),           RG(SLABS_ACACHES),           QS(noop)   },
-  { RS(SLABS_SIZE_AVG),          RG(SLABS_SIZE_AVG),          QS(noop)   },
-  { RS(SLABS_SIZE_MIN),          RG(SLABS_SIZE_MIN),          QS(noop)   },
-  { RS(SLABS_SIZE_MAX),          RG(SLABS_SIZE_MAX),          QS(noop)   },
-  { RS(SLABS_SIZE_ACTIVE),       RG(SLABS_SIZE_ACTIVE),       QS(noop)   },
-  { RS(SLABS_SIZE_TOTAL),        RG(SLABS_SIZE_TOTAL),        QS(noop)   },
-
-  { RS(SLABS_DELTA_OBJS),        RG(SLABS_DELTA_OBJS),        QS(noop)   },
-  { RS(SLABS_DELTA_AOBJS),       RG(SLABS_DELTA_AOBJS),       QS(noop)   },
-  { RS(SLABS_DELTA_PAGES),       RG(SLABS_DELTA_PAGES),       QS(noop)   },
-  { RS(SLABS_DELTA_SLABS),       RG(SLABS_DELTA_SLABS),       QS(noop)   },
-  { RS(SLABS_DELTA_ASLABS),      RG(SLABS_DELTA_ASLABS),      QS(noop)   },
-  { RS(SLABS_DELTA_CACHES),      RG(SLABS_DELTA_CACHES),      QS(noop)   },
-  { RS(SLABS_DELTA_ACACHES),     RG(SLABS_DELTA_ACACHES),     QS(noop)   },
-  { RS(SLABS_DELTA_SIZE_AVG),    RG(SLABS_DELTA_SIZE_AVG),    QS(noop)   },
-  { RS(SLABS_DELTA_SIZE_MIN),    RG(SLABS_DELTA_SIZE_MIN),    QS(noop)   },
-  { RS(SLABS_DELTA_SIZE_MAX),    RG(SLABS_DELTA_SIZE_MAX),    QS(noop)   },
-  { RS(SLABS_DELTA_SIZE_ACTIVE), RG(SLABS_DELTA_SIZE_ACTIVE), QS(noop)   },
-  { RS(SLABS_DELTA_SIZE_TOTAL),  RG(SLABS_DELTA_SIZE_TOTAL),  QS(noop)   },
-
-  { RS(SLABNODE_NAME),           RG(SLABNODE_NAME),           QS(str)    },
-  { RS(SLABNODE_OBJS),           RG(SLABNODE_OBJS),           QS(u_int)  },
-  { RS(SLABNODE_AOBJS),          RG(SLABNODE_AOBJS),          QS(u_int)  },
-  { RS(SLABNODE_OBJ_SIZE),       RG(SLABNODE_OBJ_SIZE),       QS(u_int)  },
-  { RS(SLABNODE_OBJS_PER_SLAB),  RG(SLABNODE_OBJS_PER_SLAB),  QS(u_int)  },
-  { RS(SLABNODE_PAGES_PER_SLAB), RG(SLABNODE_PAGES_PER_SLAB), QS(u_int)  },
-  { RS(SLABNODE_SLABS),          RG(SLABNODE_SLABS),          QS(u_int)  },
-  { RS(SLABNODE_ASLABS),         RG(SLABNODE_ASLABS),         QS(u_int)  },
-  { RS(SLABNODE_USE),            RG(SLABNODE_USE),            QS(u_int)  },
-  { RS(SLABNODE_SIZE),           RG(SLABNODE_SIZE),           QS(ul_int) },
+/*  setsfunc                     sortfunc
+    ---------------------------  ---------  */
+  { RS(noop),                    QS(ul_int) },
+  { RS(extra),                   QS(noop)   },
+
+  { RS(SLABS_OBJS),              QS(noop)   },
+  { RS(SLABS_AOBJS),             QS(noop)   },
+  { RS(SLABS_PAGES),             QS(noop)   },
+  { RS(SLABS_SLABS),             QS(noop)   },
+  { RS(SLABS_ASLABS),            QS(noop)   },
+  { RS(SLABS_CACHES),            QS(noop)   },
+  { RS(SLABS_ACACHES),           QS(noop)   },
+  { RS(SLABS_SIZE_AVG),          QS(noop)   },
+  { RS(SLABS_SIZE_MIN),          QS(noop)   },
+  { RS(SLABS_SIZE_MAX),          QS(noop)   },
+  { RS(SLABS_SIZE_ACTIVE),       QS(noop)   },
+  { RS(SLABS_SIZE_TOTAL),        QS(noop)   },
+
+  { RS(SLABS_DELTA_OBJS),        QS(noop)   },
+  { RS(SLABS_DELTA_AOBJS),       QS(noop)   },
+  { RS(SLABS_DELTA_PAGES),       QS(noop)   },
+  { RS(SLABS_DELTA_SLABS),       QS(noop)   },
+  { RS(SLABS_DELTA_ASLABS),      QS(noop)   },
+  { RS(SLABS_DELTA_CACHES),      QS(noop)   },
+  { RS(SLABS_DELTA_ACACHES),     QS(noop)   },
+  { RS(SLABS_DELTA_SIZE_AVG),    QS(noop)   },
+  { RS(SLABS_DELTA_SIZE_MIN),    QS(noop)   },
+  { RS(SLABS_DELTA_SIZE_MAX),    QS(noop)   },
+  { RS(SLABS_DELTA_SIZE_ACTIVE), QS(noop)   },
+  { RS(SLABS_DELTA_SIZE_TOTAL),  QS(noop)   },
+
+  { RS(SLABNODE_NAME),           QS(str)    },
+  { RS(SLABNODE_OBJS),           QS(u_int)  },
+  { RS(SLABNODE_AOBJS),          QS(u_int)  },
+  { RS(SLABNODE_OBJ_SIZE),       QS(u_int)  },
+  { RS(SLABNODE_OBJS_PER_SLAB),  QS(u_int)  },
+  { RS(SLABNODE_PAGES_PER_SLAB), QS(u_int)  },
+  { RS(SLABNODE_SLABS),          QS(u_int)  },
+  { RS(SLABNODE_ASLABS),         QS(u_int)  },
+  { RS(SLABNODE_USE),            QS(u_int)  },
+  { RS(SLABNODE_SIZE),           QS(ul_int) },
 
  // dummy entry corresponding to PROCPS_SLABINFO_logical_end ...
-  { NULL,                        NULL,                        NULL       }
+  { NULL,                        NULL       }
 };
 
     /* please note,
@@ -360,10 +298,8 @@ static struct {
 enum slabinfo_item PROCPS_SLABINFO_logical_end = PROCPS_SLABNODE_SIZE + 1;
 
 #undef setNAME
-#undef getNAME
 #undef srtNAME
 #undef RS
-#undef RG
 #undef QS
 
 
@@ -923,29 +859,34 @@ PROCPS_EXPORT int procps_slabinfo_unref (
 
 // --- variable interface functions -------------------------------------------
 
-PROCPS_EXPORT signed long procps_slabinfo_get (
+PROCPS_EXPORT struct slabinfo_result *procps_slabinfo_get (
         struct procps_slabinfo *info,
         enum slabinfo_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_SLABINFO_logical_end)
-        return -EINVAL;
+        return NULL;
 
     /* we will NOT read the slabinfo file with every call - rather, we'll offer
        a granularity of 1 second between reads ... */
     cur_secs = time(NULL);
     if (1 <= cur_secs - sav_secs) {
-        if ((rc = read_slabinfo_failed(info)))
-            return rc;
+        if (read_slabinfo_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_SLABINFO_noop)
+        info->get_this.result.ul_int = 0;
+    Item_table[item].setsfunc(&info->get_this, &info->hist, &info->nul_node);
+
+    return &info->get_this;
 } // end: procps_slabinfo_get
 
 

diff --git a/proc/slabinfo.h b/proc/slabinfo.h
index 6faa866ddafbdd8cfd07345286c42a2c5cabdc88..2fe2d79a7baa4f55536f332f923faec9f4bb735c 100644 (file)
--- a/proc/slabinfo.h
+++ b/proc/slabinfo.h
@@ -95,8 +95,11 @@ struct slabinfo_reap {
 };
 
 
-#define PROCPS_SLABINFO_VAL(rel_enum,type,stack) \
-    stack -> head [ rel_enum ] . result . type
+#define PROCPS_SLABINFO_GET( slabinfo, actual_enum, type ) \
+    procps_slabinfo_get( slabinfo, actual_enum ) -> result . type
+
+#define PROCPS_SLABINFO_VAL( relative_enum, type, stack ) \
+    stack -> head [ relative_enum ] . result . type
 
 
 struct procps_slabinfo;
@@ -105,7 +108,7 @@ int procps_slabinfo_new   (struct procps_slabinfo **info);
 int procps_slabinfo_ref   (struct procps_slabinfo  *info);
 int procps_slabinfo_unref (struct procps_slabinfo **info);
 
-signed long procps_slabinfo_get (
+struct slabinfo_result *procps_slabinfo_get (
     struct procps_slabinfo *info,
     enum slabinfo_item item);