errlog std::ostream

common/errlogstream.h

@@ -0,0 +1,80 @@
+#ifndef ERRLOGSTREAM_H
+#define ERRLOGSTREAM_H
+
+#include <streambuf>
+#include <ostream>
+#include <vector>
+#include <algorithm>
+
+#include <assert.h>
+
+#include <errlog.h>
+
+//! output only stream buffer which write to the epics errlog
+struct errlog_streambuf : public std::streambuf
+{
+    typedef std::vector<char> buffer_t;
+
+    errlog_streambuf(bool block=false, size_t blen=126)
+        :std::streambuf()
+        ,p_outbuf(std::max(blen, size_t(16u))+2)
+        ,p_block(block)
+    {
+        p_reset();
+    }
+    virtual ~errlog_streambuf() {sync();}
+    virtual int_type overflow(int_type c)
+    {
+        size_t nwrite = pptr()-pbase();
+        assert(nwrite<p_outbuf.size()-1);
+        if(c!=traits_type::eof()) {
+            p_outbuf[nwrite++] = traits_type::to_char_type(c);
+        }
+        p_flush(nwrite);
+        p_reset();
+        return traits_type::not_eof(c);
+    }
+
+    //! flush local buffer to global errlog buffer.
+    //! if block=true then also calls errlogFlush()
+    virtual int sync()
+    {
+        size_t nwrite = pptr()-pbase();
+        assert(nwrite<p_outbuf.size()-1);
+        p_flush(nwrite);
+        p_reset();
+        return 0;
+    }
+
+private:
+    void p_reset()
+    {
+        char *B = &p_outbuf[0];
+        setp(B, B+p_outbuf.size()-2); // reserve one char for overflow()s arg and one for nil
+    }
+    void p_flush(size_t nwrite)
+    {
+        if(nwrite) {
+            p_outbuf[nwrite++] = '\0';
+            errlogMessage(&p_outbuf[0]);
+            if(p_block)
+                errlogFlush();
+        }
+    }
+
+    buffer_t p_outbuf;
+    bool p_block;
+};
+
+struct errlog_ostream : public std::ostream
+{
+    errlog_ostream(bool block=false, size_t blen=126)
+        :std::ostream(&p_strm)
+        ,p_strm(block, blen)
+    {}
+    virtual ~errlog_ostream() {}
+private:
+    errlog_streambuf p_strm;
+};
+
+#endif // ERRLOGSTREAM_H