--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/xml/doAmazonRequest.php	Sun Jan 06 07:17:03 2019 -0500
@@ -0,0 +1,94 @@
+<?php
+include_once "ywww/dlog.php";
+
+include_once "private/web.php";
+include "aws_signed_request.php";  
+
+function doAmazonRequest($ext, $parameters, $try, $dbl='x', $wantXML=True)
+{
+  global $public_key, $private_key;
+  $requestURI = $_SERVER['REQUEST_URI'];
+  $requestIP = $_SERVER['REMOTE_ADDR'];
+  $file_data=$ext;
+  ksort($parameters);
+  foreach ($parameters as $i=>$d) {
+    $file_data.='&'.$i.'='.$d;
+  }
+  $gotit=0;
+  $url=aws_signed_request($ext,$parameters,$public_key,$private_key);  
+  //dl("search: $ext $public_key $private_key\n$url\n".print_r($parameters,TRUE)."\n");
+  for ($i=1; $i<=$try; $i++) {
+    $crl = curl_init();
+    $timeout = 5;
+    curl_setopt ($crl, CURLOPT_URL,$url);
+    curl_setopt ($crl, CURLOPT_ENCODING , "gzip"); 
+    curl_setopt ($crl, CURLOPT_RETURNTRANSFER, 1);
+    curl_setopt ($crl, CURLOPT_CONNECTTIMEOUT, $timeout);
+    $semaphore = new SyncSemaphore("Amazon");
+    $gotit = $semaphore->lock(1000);
+    if (!$gotit) {
+      dl("Got it: ".(int)$gotit." $requestIP $dbl\n");
+      $gotit=$semaphore->lock(1000);
+      dl("Got it: ".(int)$gotit." $requestIP $dbl"."a\n");
+    }
+    $output = curl_exec($crl);
+    //dl("nai2: ".strlen($output)."\n");
+
+    curl_close($crl);
+    usleep(500000);
+    if ($gotit) {
+      $semaphore->unlock();
+    }
+    else {
+      dl("W/o lock for $requestIP $dbl"."b\n");
+    }
+    $mm=array();
+    $xml = new SimpleXMLElement($output);	
+    if (preg_match("/<Error>/",$output,$mm)) {
+      $resName=$xml->getName();
+      $code=$xml->Error->Code;
+      if ($code) {
+	$message=$xml->Error->Message;
+      }
+      else {
+	$code=$xml->Items->Request->Errors->Error->Code;
+	$message=$xml->Items->Request->Errors->Error->Message;
+      }
+      dl("Losing $i: $dbl ".
+	 $mm[0].", $resName, $code, $requestIP, $requestURI\n");
+      if ($code!='RequestThrottled') {
+	dl("message: $message\n");
+	if ($code=='AWS.InvalidParameterValue' && strpos($message,"for ItemId.")>0) {
+	  // Check for common problem and try to fix...
+	  $spd=$parameters['ItemId'];
+	  if (strpos($spd,'/')>0) {
+	    $isbnMaybe=substr($spd,0,strpos($spd,'/'));
+	    $parameters['ItemId']=$isbnMaybe;
+	    if (isset($parameters['Keywords'])) {
+		$parameters['Keywords']=urlencode($isbnMaybe);
+	      }
+	    dl("retrying with $isbnMaybe\n");
+	    return doAmazonRequest($ext,$parameters,$try,$dbl);
+	  }
+	}
+	if ($code=="") {
+	  dl("error elt:\n$output\n");
+	}
+	throw new Exception($code);
+      }
+    }
+    else {
+      if ($wantXML) {
+	return $xml;
+      }
+      else {
+	//dl("returning ".strlen($output)."\n");
+	return $output;
+      }
+    }
+    usleep(100000*$i); // Try to reduce throttling until we get a 
+    // principled solution in place
+  }
+  throw new Exception("ThrottledRepeatedly");
+}
+?>