JSON Links implementation
The lnkConst.c implementation is not yet complete, no support for arrays of strings (JMOP). Link error messages should display their record & field name, which is not yet possible. The ability to embed links as parameters to other link types is not complete yet; this will be required for the calc link type. This code currently passes all existing tests, but additional tests are needed for the new functionality.
This commit is contained in:
Andrew Johnson
@@ -11,7 +11,7 @@ SRC_DIRS += $(STDDIR)/link
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DBD += links.dbd
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# dbRecStd_SRCS += ...
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dbRecStd_SRCS += lnkConst.c
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HTMLS += links.html
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+37
-18
@@ -1,7 +1,7 @@
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=head1 Link Types
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=head1 JSON Links
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Links are an extensible mechanism for adding new kinds of database link,
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using JSON for link addresses.
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JSON Links are an extensible mechanism for adding new kinds of database link,
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using JSON for the link address.
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The following link types are available in this release:
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=over
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@@ -12,6 +12,8 @@ The following link types are available in this release:
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=item * L<Channel Access|/"Channel Access Link ca">
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=item * L<Calc|/"Calculation Link calc">
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=back
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=head2 Using Links
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@@ -21,35 +23,36 @@ must appear inside a pair of braces C< {} > expressed as a JSON
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(L<JavaScript Object Notation|http://www.json.org/>) object, which allows link
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parameters to be defined as needed.
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Note that due to the required presence of the double-quote characters in the
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JSON strings in a link field value string in a database file, it will usually
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be necessary to escape all double-quote characters in the JSON object by
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preceding them with a backslash C< \ > character.
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Database configuration tools that support this link mechanism must be careful
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to handle these escapes correctly on reading and writing string values from/to
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a .db file.
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=head2 Filter Reference
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=head2 Link Type Reference
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=cut
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link(const,lsetConst)
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link(const, lnkConstIf)
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=head3 Constant Link C<"const">
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...
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Constant links provide one or more values at link initalization time, but do not return
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any data when their C<getValue()> routine is called. Most record types support the use of
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constant links by calling C<recGblInitConstantLink()> at initialization, which results in
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the constant value being loaded into the target field at that time.
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=head4 Parameters
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...
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A const link takes a parameter which may be an integer, double or string, or an array of
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those types. If an array contains both integers and double values the integers will be
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promoted to doubles. Mixing strings and numbers in an array will result in an error.
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=head4 Example
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=head4 Examples
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...
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{const: 3.14159265358979}
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{const: "Pi"}
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{const: [1, 2.718281828459, 3.14159265358979]}
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{const: ["One", "e", "Pi"]}
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=cut
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link(db,lsetDatabase)
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#link(db, lnkDbIf)
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=head3 Database Link C<"db">
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@@ -65,7 +68,7 @@ link(db,lsetDatabase)
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=cut
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link(ca,lsetChannelAccess)
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#link(ca, lnkCaIf)
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=head3 Channel Access Link C<"ca">
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@@ -90,3 +93,19 @@ link(ca,lsetChannelAccess)
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...
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=cut
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#link(calc, lnkCalcIf)
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=head3 Calculation Link C<"calc">
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...
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=head4 Parameters
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...
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=head4 Example
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...
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=cut
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@@ -0,0 +1,412 @@
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/*************************************************************************\
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* Copyright (c) 2016 UChicago Argonne LLC, as Operator of Argonne
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* National Laboratory.
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* EPICS BASE is distributed subject to a Software License Agreement found
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* in file LICENSE that is included with this distribution.
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\*************************************************************************/
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/* lnkConst.c */
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#include <string.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include "dbDefs.h"
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#include "errlog.h"
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#include "epicsAssert.h"
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#include "epicsTypes.h"
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#include "dbAccessDefs.h"
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#include "dbConvertFast.h"
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#include "dbLink.h"
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#include "dbJLink.h"
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#include "epicsExport.h"
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/* Change 'undef' to 'define' to turn on debug statements: */
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#undef DEBUG_LINK
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#ifdef DEBUG_LINK
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int lnkConstDebug = 10;
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# define IFDEBUG(n) \
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if (lnkConstDebug >= n) /* block or statement */
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#else
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# define IFDEBUG(n) \
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if(0) /* Compiler will elide the block or statement */
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#endif
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typedef long (*FASTCONVERT)();
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typedef struct clink {
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struct jlink jlink; /* embedded */
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int nElems;
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enum {s0, si32, sf64, sc40, a0, ai32, af64, ac40} type;
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union {
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epicsInt32 scalar_integer;
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epicsFloat64 scalar_double;
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char * scalar_string;
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void *pmem;
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epicsInt32 *pintegers;
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epicsFloat64 *pdoubles;
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char **pstrings;
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} value;
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} clink;
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static lset lnkConst_lset;
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/*************************** jlif Routines **************************/
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static jlink* lnkConst_alloc(struct link *plink) {
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clink *clink = calloc(1, sizeof(struct clink));
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IFDEBUG(10)
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printf("lnkConst_alloc()\n");
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clink->type = s0;
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clink->nElems = 0;
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clink->value.pmem = NULL;
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IFDEBUG(10)
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printf("lnkConst_alloc -> const@%p\n", clink);
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return &clink->jlink;
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}
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static void lnkConst_free(jlink *pjlink) {
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clink *clink = CONTAINER(pjlink, struct clink, jlink);
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IFDEBUG(10)
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printf("lnkConst_free(const@%p)\n", pjlink);
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switch (clink->type) {
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int i;
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case ac40:
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for (i=0; i<clink->nElems; i++)
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free(clink->value.pstrings[i]);
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/* fall through */
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case ai32:
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case af64:
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free(clink->value.pmem);
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default:
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break;
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}
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free(clink);
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}
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static jlif_result lnkConst_integer(jlink *pjlink, long num) {
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clink *clink = CONTAINER(pjlink, struct clink, jlink);
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IFDEBUG(10)
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printf("lnkConst_integer(const@%p, %ld)\n", pjlink, num);
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switch (clink->type) {
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void *buf;
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int nElems;
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case s0:
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clink->nElems = 1;
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clink->type = si32;
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clink->value.scalar_integer = num;
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break;
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case a0:
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clink->type = ai32;
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/* fall thorough */
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case ai32:
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nElems = clink->nElems + 1;
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buf = realloc(clink->value.pmem, nElems * sizeof(epicsInt32));
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if (!buf) break;
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clink->value.pmem = buf;
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clink->value.pintegers[clink->nElems] = num;
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clink->nElems = nElems;
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break;
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case af64:
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nElems = clink->nElems + 1;
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buf = realloc(clink->value.pmem, nElems * sizeof(epicsFloat64));
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if (!buf) break;
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clink->value.pmem = buf;
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clink->value.pdoubles[clink->nElems++] = num;
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break;
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case ac40:
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errlogPrintf("lnkConst: Mixed data types in array\n");
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/* FIXME ??? */
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default:
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return jlif_stop;
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}
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return jlif_continue;
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}
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static jlif_result lnkConst_boolean(jlink *pjlink, int val) {
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IFDEBUG(10)
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printf("lnkConst_boolean(const@%p, %d)\n", pjlink, val);
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return lnkConst_integer(pjlink, val);
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}
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static jlif_result lnkConst_double(jlink *pjlink, double num) {
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clink *clink = CONTAINER(pjlink, struct clink, jlink);
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IFDEBUG(10)
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printf("lnkConst_double(const@%p, %g)\n", pjlink, num);
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switch (clink->type) {
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epicsFloat64 *f64buf;
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int nElems, i;
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case s0:
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clink->nElems = 1;
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clink->type = sf64;
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clink->value.scalar_double = num;
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break;
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case a0:
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clink->type = af64;
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/* fall thorough */
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case af64:
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nElems = clink->nElems + 1;
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f64buf = realloc(clink->value.pmem, nElems * sizeof(epicsFloat64));
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if (!f64buf) break;
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clink->value.pdoubles = f64buf;
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clink->value.pdoubles[clink->nElems++] = num;
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break;
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case ai32: /* promote earlier ai32 values to af64 */
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f64buf = calloc(clink->nElems + 1, sizeof(epicsFloat64));
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if (!f64buf) break;
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for (i = 0; i < clink->nElems; i++) {
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f64buf[i] = clink->value.pintegers[i];
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}
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f64buf[clink->nElems++] = num;
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free(clink->value.pmem);
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clink->value.pdoubles = f64buf;
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clink->type = af64;
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break;
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case ac40:
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errlogPrintf("lnkConst: Mixed data types in array\n");
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/* FIXME ??? */
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default:
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return jlif_stop;
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}
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return jlif_continue;
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}
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static jlif_result lnkConst_string(jlink *pjlink, const char *val, size_t len) {
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clink *clink = CONTAINER(pjlink, struct clink, jlink);
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IFDEBUG(10)
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printf("lnkConst_string(const@%p, \"%.*s\")\n", clink, (int) len, val);
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if (len > MAX_STRING_SIZE)
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len = MAX_STRING_SIZE;
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if (clink->type == s0) {
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char *buf = malloc(len + 1);
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if (!buf)
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return jlif_stop;
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strncpy(buf, val, len);
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buf[len] = '\0';
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clink->nElems = 1;
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clink->type = sc40;
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clink->value.scalar_string = buf;
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return jlif_continue;
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}
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/* FIXME Implement a0 and ac40 */
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/* FIXME How to handle ai32 and af64? */
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errlogPrintf("lnkConst: Mixed data types in array\n");
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return jlif_stop;
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}
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static jlif_result lnkConst_start_array(jlink *pjlink) {
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clink *clink = CONTAINER(pjlink, struct clink, jlink);
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IFDEBUG(10)
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printf("lnkConst_start_array(const@%p)\n", pjlink);
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if (clink->type != s0) {
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errlogPrintf("lnkConst: Embedded array value\n");
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return jlif_stop;
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}
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clink->type = a0;
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return jlif_continue;
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}
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static jlif_result lnkConst_end_array(jlink *pjlink) {
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IFDEBUG(10)
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printf("lnkConst_end_array(const@%p)\n", pjlink);
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return jlif_continue;
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}
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static struct lset* lnkConst_get_lset(const jlink *pjlink) {
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IFDEBUG(10)
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printf("lnkConst_get_lset(const@%p)\n", pjlink);
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return &lnkConst_lset;
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}
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static void lnkConst_report(const jlink *pjlink) {
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clink *clink = CONTAINER(pjlink, struct clink, jlink);
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IFDEBUG(10)
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printf("lnkConst_report(const@%p)\n", clink);
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/* FIXME Implement! */
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}
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/*************************** lset Routines **************************/
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static long lnkConst_loadScalar(struct link *plink, short dbrType, void *pbuffer)
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{
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clink *clink = CONTAINER(plink->value.json.jlink, struct clink, jlink);
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long status;
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IFDEBUG(10)
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printf("lnkConst_loadScalar(const@%p, %d, %p)\n",
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clink, dbrType, pbuffer);
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switch (clink->type) {
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case si32:
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status = dbFastPutConvertRoutine[DBF_LONG][dbrType]
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(&clink->value.scalar_integer, pbuffer, NULL);
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break;
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case sf64:
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status = dbFastPutConvertRoutine[DBF_DOUBLE][dbrType]
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(&clink->value.scalar_double, pbuffer, NULL);
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break;
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case sc40:
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status = dbFastPutConvertRoutine[DBF_STRING][dbrType]
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(clink->value.scalar_string, pbuffer, NULL);
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break;
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case ai32:
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status = dbFastPutConvertRoutine[DBF_LONG][dbrType]
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(clink->value.pintegers, pbuffer, NULL);
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break;
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case af64:
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status = dbFastPutConvertRoutine[DBF_DOUBLE][dbrType]
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(clink->value.pdoubles, pbuffer, NULL);
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break;
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default:
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status = S_db_badField;
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break;
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}
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return status;
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}
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static long lnkConst_loadArray(struct link *plink, short dbrType, void *pbuffer,
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long *pnReq)
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{
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clink *clink = CONTAINER(plink->value.json.jlink, struct clink, jlink);
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short dbrSize = dbValueSize(dbrType);
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char *pdest = pbuffer;
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int nElems = clink->nElems;
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FASTCONVERT conv;
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long status;
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IFDEBUG(10)
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printf("lnkConst_loadArray(const@%p, %d, %p, (%ld))\n",
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clink, dbrType, pbuffer, *pnReq);
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if (nElems > *pnReq)
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nElems = *pnReq;
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switch (clink->type) {
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int i;
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case si32:
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status = dbFastPutConvertRoutine[DBF_LONG][dbrType]
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(&clink->value.scalar_integer, pdest, NULL);
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break;
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||||
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case sf64:
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status = dbFastPutConvertRoutine[DBF_DOUBLE][dbrType]
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(&clink->value.scalar_double, pdest, NULL);
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break;
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||||
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case sc40:
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status = dbFastPutConvertRoutine[DBF_STRING][dbrType]
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(clink->value.scalar_string, pbuffer, NULL);
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break;
|
||||
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case ai32:
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conv = dbFastPutConvertRoutine[DBF_LONG][dbrType];
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for (i = 0; i < nElems; i++) {
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conv(&clink->value.pintegers[i], pdest, NULL);
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pdest += dbrSize;
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}
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||||
status = 0;
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||||
break;
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||||
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||||
case af64:
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||||
conv = dbFastPutConvertRoutine[DBF_DOUBLE][dbrType];
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for (i = 0; i < nElems; i++) {
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conv(&clink->value.pdoubles[i], pdest, NULL);
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pdest += dbrSize;
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||||
}
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||||
status = 0;
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||||
break;
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||||
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default:
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||||
status = S_db_badField;
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||||
}
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||||
*pnReq = nElems;
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return status;
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}
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||||
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static long lnkConst_getNelements(const struct link *plink, long *nelements)
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{
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IFDEBUG(10)
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printf("lnkConst_getNelements(const@%p, (%ld))\n",
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plink->value.json.jlink, *nelements);
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||||
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*nelements = 0;
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return 0;
|
||||
}
|
||||
|
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static long lnkConst_getValue(struct link *plink, short dbrType, void *pbuffer,
|
||||
epicsEnum16 *pstat, epicsEnum16 *psevr, long *pnRequest)
|
||||
{
|
||||
IFDEBUG(10)
|
||||
printf("lnkConst_loadScalar(const@%p, %d, %p, ... (%ld))\n",
|
||||
plink->value.json.jlink, dbrType, pbuffer, *pnRequest);
|
||||
|
||||
if (pnRequest)
|
||||
*pnRequest = 0;
|
||||
return 0;
|
||||
}
|
||||
|
||||
|
||||
/************************* Interface Tables *************************/
|
||||
|
||||
static lset lnkConst_lset = {
|
||||
1, 0, /* Constant, not Volatile */
|
||||
NULL, lnkConst_loadScalar, lnkConst_loadArray, NULL,
|
||||
NULL, lnkConst_getNelements, lnkConst_getValue,
|
||||
NULL, NULL, NULL,
|
||||
NULL, NULL,
|
||||
NULL, NULL,
|
||||
NULL, NULL,
|
||||
NULL
|
||||
};
|
||||
|
||||
static jlif lnkConstIf = {
|
||||
"const", lnkConst_alloc, lnkConst_free, NULL,
|
||||
NULL, lnkConst_boolean, lnkConst_integer, lnkConst_double, lnkConst_string,
|
||||
NULL, NULL, NULL, lnkConst_start_array, lnkConst_end_array,
|
||||
NULL, lnkConst_get_lset, lnkConst_report
|
||||
};
|
||||
epicsExportAddress(jlif, lnkConstIf);
|
||||
|
||||
Reference in New Issue
Block a user